With the room size you mentioned, there is no need to even mic the drums... In fact, you will really need to control your playing. The acoustics of the room is gonna be a huge problem for you guys... Is the room carpeted? If not the sound generated from all the instruments will bounce of the walls and floors. Its gonna be really nasty...
Again, based on your budget, can get E-drums? I thought E-drums are more expensive as compare to a simple acoustic drum? It is correct as mentioned by one of bro, it's easier for your sound guy to make a small set sound big than a big set sound small. But, as i said earlier, with your room size, you do not need to mic up the drums at all and there is nothing your sound guy can do to reduce the drums volume except for the drummer to control the playing and not whack so hard. Alternatively, u can dampen the drums. Check out one of the link that was discussed b4 that talks about how to dampen the drums volume.
Honestly, a good solution that is appropriate to your room size will be to use E-Drums. But as you have said, the location is not permanent and you guys will move to a larger hall so you have to decide. IF you get a acoustic drums, you need to control the playing and use simple small compact set up like the hipgig set. IF you use E-drums, no problem with volume... it can be adjusted... but you need a decent set of speakers and not those cheap speakers that makes the drum sounds funny. But if you guys are not concern about how the drum sounds... then its fine... Therefore, E-drums can solve your immediate issue of room size and potential sound problem but acoustic kit will prepare you to the next move of location but it also depends your next location will be big or not... if its similar set up with concrete flooring then its back to square one.
Hope all the comments are helpful to you.