Can I buy ebass?

No, unfortunately you can’t. I use the ebass a lot and do not sell other models.

Can I rent ebass?

No, sorry. I need it most of the time for gigs.

Is there a bass do can recommend?

This is a tricky and very personal question. The ideal bass for me can be the worst bass possible for you. It depends, for instance, on your style (plucked, bowed, combination, plucked with force or gently, funky, etc), the genre (jazz, acoustic, classical, pop, or just for practice maybe), and of course the look (it’s your buddy on stage, remember).

I have played on some EUBs though and can share some experiences. I liked the Steinberger bass: good tone and build quality, however, the design is a bit too “spacey” for me. I totally disliked the Dean Pace Bass, this is a bass guitar on a stick.
The Ergo basses are popular and relatively inexpensive (but sound a bit like fretless basses, imho). In the Netherlands, Lucas Suringar makes custom electric upright basses, and Rogier Dieges offers a semi-acoustic bass. The Stagg is hard to beat for the price, it offers a good tone for such an inexpensive bass. The playability is said to be OK, however, it is not to be compared with a custom bass.

What can I do about feedback with my double bass/eub?

Have a look at this topic

More to be added.