I always use the u87ai with the Neve. I only run instruments to the LA-610. They are both worth keeping. New tubes should not cost $300 - $500. Where did you get that figure? If you are replacing all of the tubes, you will need to get it calibrated, but I would think that the whole job should be well under $300.
If you are just doing voice overs, you don't really need a tube pre. In fact, weird tube coloring is probably the LAST thing you'd want.
Solid State pres are probably the way to go! If you want to get something cheaper than the Neve, I like the True Systems p-solo with the u87. The benefit of having a Neve is the EQ, which may come in handy for your type of work.
Hmmm, well, one thing that you can do... if you are going to buy new: order a few pres from a major website like Musiciansfriend and return the ones that you don't like. Perhaps you may discover that the 610 is the right pre for your voice? You never know...