Weddingbee boards

After our amazing epics :

http://boards.weddingbee.com/topic/my-epics-love-them-so-much-they-make-me-cry-picture-heavy

we definitely want to tip our photographers (they spent four hours with us, and gave us 289 edited photos, which I think is quite generous).  Our total package (including wedding coverage, epics, album, and some photo credit) is 2500.  I was thinking of giving a $150 tip now, and then $150 after the wedding pics if we are still happy. (that's a little above 10 percent...we really can't afford to go to twenty percent).

They are an unmarried couple.  Should I make the check out to their business name, or to one of them personally, or half the amount to each of them? (I have to mail it, so I'd rather not do cash).

Any thoughts?  I think I might be overthinking this....