Going from a x50 to a x30 objective will have a light gathering quality difference, albeit 15-20 mins or there abouts, either side of first/last light.
I had a pair of Minox 8.5x42's (BR's I think was the model), I bought them as a spare set, reasonably compact compaired to my Swarovski EL's and they were good, and for less than half the RRP of Swarovski's. I sold mine on however once my 10x42 EL's were repaired.
Hunters Cabin was selling some Minox at a reduced rate in the classifieds, might be worth a PM to him and see what he has.
If I had Minox from the start, I don't think I would ever have changed, but I was quite attached to my EL's.
The 10x42 EL's I have have good light gathering quality, I have infact compaired them to a set of 8x30, Offroad Gary had them, there was a noticable difference in the field.
You always need to compramise something to gain on something else unfortunatley, but I would try your best to get hold as many pairs of binos in your price bracket and let your eyes do the talking, not the name. Swarovski are expencive, but you do get a very good warranty package with them also.
Good luck
TJ