Non-refundable/non-transferable?

I don't think that's typical. Is it a very inexpensive rental? Like a church or something?

No, I've never heard of this.

$2900 for the ceremony and reception

I would not do that. What if they go out of business, what if they breach contract? Too many what ifs for me to just give my money away without there being a clause stating that I get at least some of it back if something goes wrong. Is there a clause stating if something goes wrong they will refund you your money?

This isn't the norm in my experience. Yes, sometimes the deposited vary as high as 50% down, but the entire thing up front with a non-refundable and non- transferable policy sounds extremely questionable in my opinion.

100% non-refundable sounds a little fishy to me. I'd read a lot of reviews on the place.

I would not pay 100% upfront in general and especially if there is nothing in the contract laying out situations in which the payment is refundable (breach of contract, inability to provide venue due to fire, flood, etc). Btw, if these things are not in the contract for whatever venue you choose, ask them to include it. My deposit was 50%.