I met a fashion photographer once who got nice grain effects with Provia 400F, probably pushed two stops.
Check the clearance section of http://www.freestylephoto.biz/ and you might find some cold stored Fuji films (and maybe others) that are older and grainier. They had 100-foot rolls of RMS really cheap not long ago, and probably still have some. I bought 100 rolls of RMS in 120 from them, and it's been fine. It's designed for pushing, but was discontinued with the introduction of Provia 400F. RMS has sharper, bigger grain than Provia 400F. For really big grain, push RMS 4 stops and rate it at EI 1000.