I bought a 1980 Greco Super Real last week and it's pretty good. The prices for all the '78 to '83 jap guitars have been rising slowly for about five years as far as I can make out, and such a guitar, which is still cheaper than a secondhand LP Standard, would make a better investment than a new Gibson or a totally 'custom' Les Paul, if you get the right one.
Check out japanguitars.co.uk to see just how much some people are selling vintage jap stuff for...most people agree this guy's charging really top-whack prices, yet his guitars still sell within weeks. I noticed about a month ago he raised the price of one of his less popular guitars he'd had hanging around for months by £150, and it then sold within a couple of weeks. I think you can draw your own conclusions from that!
Remember too though - and I'm trying not to sound corny here - that every guitar is different no matter who it's made by. This is something I've finally realised after years spent on internet forums taking advice from people who say 'this guitar make is better than that one', and is partly the reason why this is my first post on this forum for weeks.
Nobody makes totally rubbish guitars these days.
If I could go through the LP buying process again, I'd take my mate's advice and just go to Denmark St and try out 30 Les Pauls and buy a genuinely 'flukey' special one, instead of hedging my bets on one guitar by one maker which the guitar forum community says is really good.
He went through the Denmark St process for a Strat, and ended up with the most ridiculously resonant (for no apparent reason) strat I've ever played. The whole thing shakes and feels like it's about to self destruct, while at the same time feeling completely solid. It's amazing. It cost him a grand second hand, but we played about half a dozen other custom shop strats in that shop which cost a lot more money, and they all felt dead in comparison.
If you're really bothered about getting an above average guitar, which you probably are if you've gone to the effort of asking on a forum, just try as many guitars as you can and wait 'til you find one that feels great to you.