Well its a Dell t3500 mobo i know the pinout but will this fit into the case?
From what I can find, probably not.
Quite a few comments out there that this board is "larger than most E-ATX boards on the market".
Suggest you measure the board, so you know what you're working with.
It'll probably fit in terms of 'height' in the Mattrexx, but width will be your deciding factor.
5.25" bays & drive cages will be a problem in most consumer cases with 'true' support for "E-ATX". Not to mention any cable pass-through/grommets are unlikely to be of any use.
I don't think you're finding one <$150, let alone <$50. That's for 'official' support. You might find a case you can squeeze it in, but that's more trial & error.
....and...