Hey.. you have David Husek in your sig... I bet definitely he can help.
I have seen $800 and $3000 transmissions do it. There is risk/reward involved in what level of transmission you buy. I would budget $2500 for the whole thing.. maybe $1200-1500 for a trans and $900 for a converter, then shifter etc.
Converter cost is the same as any. Some will work for as low as $600, but they may not be ideal for a combo. Seems like the best converters are in the $900+ range - like a PTC.
If you're 2004r is working good, it could mean just a converter change for you in that trans.
Based on your signature, you are no where near that 9sec now.. do you have something big coming? It really is a huge jump to start thinking about a 9 sec converter from the 11's or even high 10s.