First off - congrats on your upcoming twins. It's truly a hoot, although the first few months will seem like a whirlwind of chaos!!
I live in a small, rural town with the nearest Walmart being about 45 miles away and not a single Target in our state LOL. I was lucky and inherited one crib from my sister, then bought a crib & glider chair on eBay for around $100 total. Craiglist has some great deals on cribs as well. You will need to get new crib mattresses, but that's a small cost compared to the crib itself. We don't have convertible cribs - that said, our boys are 27 months and (knock wood) have not shown any interest in climbing out of their cribs yet. Our cribs don't match too carefully but I usually try to put the same sheets on each crib. That said, I really stopped caring soon after the umpteenth sheet change
I solved that by getting all blue based sheets so they basically match, no matter what.
Our kids will most likely be sharing a room for a good portion of their youth. Initially we tried using the Arm's Reach Co-sleeper (in the original size) but it didn't work so well for us - for the main reason that it only fit on DH's side of the bed, so we switched sides...then the noise that the boys made during the night proceeded to drive everyone a bit crazy...so I wound up moving into the nursery with the boys for a few months (we have a twin bed in there)
I also gave up on changing tables fairly quickly, in favor of mats that I use on the floor in whatever room we happen to be in. It was, for me, too much trouble to have to scoop up both boys to move them to wherever the changing table was, then keep an eye on the one not on the table, while keeping an eye on the one ON the table. For a long time (even now at 27 mos) I changed them on the floor on a washable, waterproof mat. I do still have a changing table that I keep diapers and PJs on in our bathroom, where they get bathed every night.
There is a discount baby place out of Williston, VT kidsurplus.com - I got our crib divider here (they were in the same crib until they really started rolling around) and several great day-to-day items.