Actually the amount available is 1,000 GBP which is about $1,874 USD. Kind of puts the OP on the edge where he could get some decent stuff for that amount, but 8 channels with variety and quality is pushing it. Basically, IMHO, the decent solid state stuff you can get at that price point will also be pretty similar in sound and performance (Sytek, RNP). The DAV BG1 would be an exception in that it runs more to the clean and transparent sound where comparable units would include Millennia and Grace which are more expensive.
There isn't too much available in the way of good tube gear at that price point. Peavey VMP-2 (used only as they are discontinued), Groove Tubes (GC was blowing out the Brick here over the holiday weekend for $200 or so) and perhaps the Goldmike pre. Sebatron is probably the next tier up and could be affordable if used. Groove Tubes did make the MP-1 which was a single channel half rack tube mic pre. They can sometimes be found used for @$250 or so. I have a couple of them and they are nice. It is more on the clean hifi sound type of tube gear though. I can certainly understand wanting to get a variety of pres to expand the palette, but at the current price point, there are limited quality options available.
I guess my bias here is to get a couple channels of pretty good preamps to go with the firepod and acquire others as money permits, rather than to get 8 channels of so-so preamps that you will want to replace in a year or two and which will have then declined significantly in value. Even at the @$250 a channel price point, however, your options for quality pres that will truly sound different will be somewhat limited. Keep in mind that the difference in sound between different pres, even really expensive ones, is a lot less distinctive than the difference in sound between mics. Nuanced is probably a more appropriate descriptor. Whether you are able to hear some of those differences will depend on the rest of your recording chain (especially your monitors) and your room. You might want to take this a bit more slowly and listen to what you are actually getting for your money as you go along, rather than jumping in with both feet (and 8 channels of additional pres) all at once.