i need a good auto airsoft gun for 35 to 75 bucks (automatic)?

A few more dollars gets you this:

JG MP5SD6

http://www.airsoftmegastore.com/ProductDetails.asp...

$79.50

Or if you don't mind dealing w/ Airsplat there are these

Well R6E M4 A1

http://www.airsplat.com/itemdesc.asp?ic=ER-WELL-R6...

$80

Well R8 G3 A3

http://www.airsplat.com/itemdesc.asp?ic=ER-WELL-R8...

$80

Which are not bad choices by any means, but will need some minor mods early on (like O-ring & reshim / regrease) to keep up to par w/ the JG.

One that is in your price range:

BE Steyr AUG

http://www.airsplat.com/Itemdesc.asp?ic=ER-BE-M8-S...

$64.95 w/ Coupon Code "BEM8"

However BE has some serious quality control issues, to the point of needing a complete teardown & mechbox rebuild very early on. Once all fixed up it's not so bad, but getting there is half the battle - definitely lives up to the addage "you get what you pay for"

cheers