If procimity to fengjia is important, I cannot help you.
But fuchun RIGHT across from the train station has rooms from 600-1000 a night (an 800 room is quite roomy) it aint the hilton, but the tvs work, you get a desk and chairs, internet (not wifi...gotto plug in your cable) and theyre super sweet, used to foreigners. many people I know live there for a few weeks when they first get to town looking for a job (we were there for 3 weeks, my wife and I).
Its been mentioned here on forumosa too, just search for it. Not near fengjia, but all the bus lines are there and ifya ever get lost when youre out and about just tell the cabi 'taizhong huo che zhan' and ull be fine. Also ifya wanna take a train (not HSR, slow train...much cheaper, but yes, slower, but MUCH cheaper) to anywhere around taiwan just walk out the front door and across the street.
downside-can be noisy cus it is across from the train station (not from the trains, but the bus station is there too and they use intercoms, and just the usual hustle and bustle of downtown)
"Knowledge alone is transitory, the outcrop subsequent to 'I desire all things'". - A. O. Spare