if I wanted to find the birth of say....Sarah Smith in approx 1865 I'd have to look a couple of years either side, so at the minimum that's 20 credits and no guarantee you've even found the right one for the vast amount of money it just cost, it's not as if they find the answers for you, you still have to trawl through them. I used to have to search for this on
microfilm at the LDS Centre - that did take hours and hours. Each quarter was about 6 films.
I paid alot of money to another site in the past for an online pay as you go type of search & will not use the site now. If you have a subscription you can search as many times as you like for no extra charge. I agree, everything is expensive, you are not obligated to use it, but no-one is obligated to provide it for free (except RootsChat - everything here is free

)
Try the site mentioned by Simon - it appears to be cheaper, based on the annual fee & seems to provide almost as much as Ancestry (if you don't have Scottish folks) - but I haven't yet used it, so don't know anything other than what Simon has said.
FreeBDM is wonderful & will eventually have all the records but at the minute is only useful to c. 1920
Trish