If you're talking about modification parts, the market is getting better, but modifying a legend is still a heck load more expensive than modifying a civic/integra. are you looking to buy a legend or specific parts in mind?
If you mean just general replacement parts and stuff, they're readily available. Anyways, I think by U.S law car companies are required to make parts for a car 10years after production. So, the last Legend was in 1995 we're guaranteed parts until 2005. Even at that I trust Acura/Honda enough that they wont just stop having parts available hehe.