Every year I go about valuing my coin collection. I have quite a few coins, so I like to use price lists, rather than researching each coin separately. I've found four: Numismedia, NGC, USA Coin Book, and PCGS. Could anyone offer an opinion how reliable these lists are? Are there any good ones I'm leaving off?
Short answer, there are no reliable price guides. The list you have is a good starting point for "averages". The most reliable sources are auction results and even then a coin can sell for $100 one week and $75 or $125 the next week. I only "value" my coins for insurance purposes and keep track of what I paid so if I do sell I can at least break even.
Price lists are only accurate from where you live and only to a certain point. A price list is only a Price Guide. A certain coin in Nevada will command a different price in Maine, Florida, Pennsylvania or Iowa.
I have found that most of the PCGS "Coin Facts" prices are on the high side. The good thing about is if a dealer wants more than that price, it had better be darn nice coin for the grade. If they are way over that, it's probably massively over priced.
The TPGs are appraising for their markets so those are market-driven appraisals but only when their brand is on them. The other ones, I don't know exactly what they're going off of. NGC, and particularly PCGS, watch their markets real closely.
If you use auction prices be sure to use the hammer price. For example, by the time Heritage is done adding shipping, sales tax and commission the selling price is 30% or more higher than the hammer price.
Wouldn't it be better to use tha all-in price with the BP ? Using the HA archive, the prices that come up are with the BP. For GC, it's without. I find that the PCGS Price Guide (and others) are generally TOO HIGH in price. I've checked the data for a fairly liquid well-bid coin, the MCMVII High Relief Saint. In MS-63, the PCGS Price Guide (online) says it is $28,500 ($3K more for flat-edge, FWIW) and a 63+ recently sold for $26,400 at HA which probably means straight 63's are probably at about $23,000 (other 63 sales are too dated). Confirming this, an MS-63 sold at GC days ago for a total price (including BP) just over $23K. In MS-65, the PCGS Price Guide says $55,000 while HA has recent sales at $44,500 which doesn't include sales tax (avoidable ?) or miniscule S&H. Again, a bit too high. BTW, an MS-67 1908 No Motto Saint should sell for about $7K or a bit under (recent sales there for HA/GC) but PCGS Price Guide has it at $9,000 which is WAY too high.
FWIW, I find the long-term TREND and/or GRAPH of prices to be more accurate for both NGC and PCGS...NOT the recent prices.
As for myself, I've used Coin World's Coin Values and found the listed prices extremely close overall, both at traditional and online dealers. Since I no longer receive a subscription I use those listed in the ANA's Numismatist as I've been a long time member. That said, you have to remember that the market changes and the gap between time of research/assembly to print may differ sharply from series to series, coin to coin. So of the many to chose from, a 5-10% variance from the price list to current market would be a guide to use.