Lot's of stuff to prepare, but there is time. A 4 foot Colombian boa is not that big. Mine is about 4' 7" and I always imagined that would seem large. He still curls up in a tiny spot, but you will need some space for proper thermal regulation.
You CAN find some very affordable deals on caging, and I'm talking about good caging. I was in the hunt at one point, and found used Boaphiles for $100 each with Flexwatt already installed, the next day in the classifieds I found a breeder willing to sell me a boa and a cage for about $160. I opted to by brand new from Pro-Line but there are many deals to be had.
Lots of folks get out of the hobby or downsize and look to get some quick $ for a cage or two.
Don't skip on thermostats or heating options.
I don't know how old you are, but getting married and having a baby are pretty big life changers, and if you are short on cash, suffice to say,,,, the snakes will be the last thing on your mind.
That said I like your enthusiasm and efforts to do this right. I think you'll get this worked out, and coming here for advice is a good move.
The person that "gifted" you the snakes didn't do you or the snakes any favors, but I'm sure they had no idea what goes into the actual keeping of some reptiles or that you were not ready. Let's hope there are no medical issues, and they take food and shed properly!
There is a person on here who's moniker is "EXPENSIVE HOBBY", and it's true.