‘09 Giant Rincon a good buy?

I want to start mountain bikeing.Some bumpy trials with few small jumps.(deff nothing bigger then 3ft yet) I used to do some BMX back in the day so I know that cheap bike starts folding like aluminum foil. I also know 500$ is lowest starting price for an Ok MB but it's the budget for now.

I am 5'7 and 140lbs, if that makes a difference.
All opinions are very welcome. BUT DON'T tell me that I need to spend a 00 just like you. I'm not you and I can get 600-650$MAX.

I am also considering...
'08 Diamondback Response Sport 9.10
'08 Diamondback Response Comp 9.10
'09 Giant Boulder 7.50
'08 Giant Yukon 7.50
'08 Raleigh Mojave 8.0 5.00

Have you ever looked at the Forge bikes. You can get a Hard-Tail 5XX in 17 or 19 inch for $380. Rock Shox Dart 1 fork’s, Joytech Alloy QR Disc 32H. Deore rear derailieur. WTB rims and saddle. Very nice bike for the money. Hayes mx2 disk brakes.
I think that Rincon is an excellent choice for an entry level bike, even the Yukon is lovely to ride. I’m telling you this because it was my choice 15 years ago when I decided to take MTB more seriously. When that one got stolen I went for a cannondale entry level at about the same price, and to be honest with you… I loved it. I still have it and use it for commuting. The frame is in perfect condition after 10 years.