I'm sure there are people more knowledgeable than me, but I find the viewfinder necessary at 21mm any how. The lens with the hood blocks the viewfinder a bit, so I get a cleaner field of view through the external viewfinder. I have read here though, that some people don't seem to mind working without it.
I've seen both the Minolta and Hexannon 28mm come up for sale here in the classifieds, both can go for under a grand. Also, a Kobalux/Avenon can be had in 28mm for under a grand as well.
Deuteronomy 23:1 --He that is wounded in the stones, or hath his privy member cut off, shall not enter into the congregation of the Lord.