Mica,
For years I used an Ampeg SVT as do may others for that harmonically rich, warm tube sound. Last year I bought a discontinued Sunn 300T(now Fender Bassman), which for my purposes works every bit as good as the Ampeg. There are other tube amps (Mesa Boogie, Eden and Aguilar come to mind), some are outrageously expensive. If you could make an all tube Alembic bass amplifier for under $2000, there's a good chance you could unseat Ampeg as the standard. You could also offer a tube preamp/solid state power amp combo as an option for those who need the extra power. I'm ready to order!
Gale