Really it's not a bad time at all. There has been a lot of desirable things being sold the last couple of months. Some of the things you mentioned went for high amounts, but there have been bargains. A1200's are going for decent prices. Same with A2000's. A4000D's are going for about what they always have. Once in awhile some things get nuts (like the plain jane A4000D motherboard that sold last night for over $360). You normally get the entire A4000D with some extra's and a mouse and keyboard for that amount.
I don't know if there ever was a "cheap" time to get into the hobby. You mentioned the A3000 for over $800. When that was a new computer and with the extra's that system has it sold for easily over $4000 when the dollar was worth twice what it is now.
Dan