I would definitely say to buy a foal if you find one that you like. There are so many out there.
#1 do you know that your mare has had a foal in the past?
#2 consult with your vet and do a complete check to make sure she is healthy- and still there could be complications.
I bought a mare and didn't know she was in foal when I purchased her- she is 5 years old. I was a freak when I found out as I have had no foaling experiences and didn't want anything to my mare. Also if you buy a foal you don't miss out on riding time! Just something to consider!