Hi George!! Thanks for the kind words! I haven't used print price guides for years other than to identify pressings, etc. The price information is outdated at printing and the vinyl market swings wide, high, and fast.
Hey Madness! You are right on and the percentage of discovered repackagers have hit the "still sealed" market hard, Otherwise you would have done somewhat better on your Beatles LP.
Record pricing is a rather difficult thing and is based on vinyl and cover condition, pressing order (which is sometimes a journey through the arcane) and of course, desirability; supply and demand.
What was valuable two years ago maybe worthless today and pricey again two years from then. Bruce Springsteen material is an excellent example of how fickle the market can be in pricing an artists discography.
You might purchase of the Osborne price guides just for the dealer information and guide to grading record condition.
In terms of other resources,, with many single artists there are web pages, fan sites, etc., and that is also true of genres such as rockabilly, R & B, rock, etc. People who haunt these sites seem to have little else to do but research the most obscure facts about any artist or pressings and are usually more than willing to help a neophyte collector or dealer.
Good luck with your LPs and if I can be of further assistance, dont hesitate to ask!!
Best,
Zip