There are already a few options for those who want to program AVR's in basic, some open source.
http://www.fastavr.com/
http://code.google.com/p/dk-basic/
http://www.seanet.com/~karllunt/klbasic_main.html
Given several options already exist some free other inexpensive, and yet you don't see many AVR projects that use them I don't think there is much of a market for a new version.