Let's face it, price guides are essentially a scam. A great big money grab on collector's of almost anything. Anything that's collectible are like stocks in the stock market, constantly fluctuating based on the whims and desires of the collectors at large (aka the market). You wouldn't buy or sell a share of stock based on a static price out of a book that's updated MAYBE once a year, taken from who knows where, collectibles are no different. That's not to say price guides don't have some use, it's just unfortunate that their use really has little to do with what people mainly buy them for in the first place... the prices.
If you've ever used a price guide before normally the prices stated in the book are for the top condition specimen, and even if you had a perfect item that's typically a bloated price that you'd probably never get, because no one wants to pay the top dollar. Usually it's the price you could expect to pay if you were to buy a perfect item from a retailer. So with that in mind you can at least check your prices knowing it's likely to be below the stated price. Goldmine appears to be an entirely different bird, its prices are all over the place really making the advertised use of the guide useless. Not only are a lot of their prices highly overstated, but highly understated as well. Out of a small sample of records I looked up, about half came out priced too high (like a $40 record that normally sells for $10 or less online in NM condition) and half too low (like a record that consistently sells online for $500-600 in VG-NM condition they have listed for $200 NM, lower than a repressing they have for the same album sells for less than that!).
Pricing on mono vs stereo seems entirely out of whack too. I understand it's a commonly held belief that up to say 1967 stereo is actually worth more than mono releases because in the early years of stereo they were actually priced at a $1 more than mono and didn't sell as many, then in the late 1960's when mono was being phased out it actually flipped and mono was more expensive to buy so anything release 1967 and later in mono is worth more, but the current market doesn't reflect that. If you look a sites like Discogs or search albums on eBay you'll notice albums released in both stereo and mono at any time are much rarer and go for higher prices in mono. So Goldmine reflects a trend in this area that seems to no longer be the norm.
So is there any point to buying a price guide that's essentially all over the place compared to actual market sales and still following trends that are no longer happening? It depends. If you're someone whose not a collector, say you inherited someone's collection and your looking to sell it off and need an idea of value I would not look here, or any price guide for that matter. Your best option for current value is current sales, and Goldmine is far from that on all accounts. Look to eBay sold listings, and sales history on sites like Discogs. It's not going to take any longer to do an album search there than in would searching through this book and trying to figure out if Goldmine's price is over or under stated, and by looking at actual sales you can price your items to sell, not sit around forever or the even worse scenario sell them for less than their currently going for.
If you're a collector of modern day artists and releases I wouldn't bother with this book either. It's pretty clear the author is in some regards more familiar with the rarity of pre-1990's releases. Take for example the Alternate Rock group Maroon 5. Goldmine has only one of their LP's listed (Song's About Jane) and it's listed at a whopping $15.00!! A simple eBay search will lead you to discover just how high in demand Maroon 5 LP's are. The group only released very small pressings of their albums through their website, not through retail stores or other websites so on average their albums sell for $150 in VG+ condition. A NM or unopened copy of Song's About Jane recently sold for over $200. So I don't think you'd be able to find even the cover alone for $15!
So now that I've pretty much talked you out of buying this book, let me tell you why in the end I'm still not disappointed with the purchase. Aside from the fact Goldmine's prices might have well have been randomly pulled out of a hat on 75-80% of their listings, the book is still well put together and while the prices may not be worth putting much stock in the other information can be helpful. If you're into the big artists like Elvis, the Beach Boys, the Beatles, etc this book would be helpful in delving through the numerous versions and pressings and while I would't put much stock in their prices you can get a fairly decent idea of what might be rarer at least as the book seems to be somewhat correct in the pricing range within an artist, meaning a high priced Elvis album might be over or under priced but it's still worth more than their listing for the $10 LP (even if it's going for $40). It's confusing I know, but if you look up enough albums and compare them to the actual market price you can somewhat crack the glaring inaccuracies of the prices and at least determine some useful information.
Overall, if you're looking for an additional source this book might help out, for me it's basically my last resort which sometimes you'll find is better than nothing. If nothing else it's probably worth just flipping through the pages and finding albums you never knew existed. I wouldn't use it to sell anything, and I wouldn't use it to determine how much I should pay for something unless I couldn't find prior sales anywhere else, which has happened a couple times with some less popular artists, but you have to have done enough comparing between the book and online sales on other albums to kind of be able to estimate a more realistic price. Also as a side note the book only contains info on full length albums, no 45's or singles. That was fine with me as I'm not into those, but I was bummed to find no soundtracks either, or albums with various artists unrelated to soundtracks.