The other aspect of an inexpensive regulator is quality. I recently had to replace my regulator because it was leaking. I bought a no-name one from the LHBS to save $20. It is now in the trash and I went back to the one I know works well: http://www.micromatic.com/draft-keg-beer/regulators-pid-642-2.html
And it has been working well ever since.
I bought a 2nd regulator on eBay years ago. It works just fine. Was probably $35 at the time, a little cheaper than the regulators at the LHBS. Maybe I got lucky.