We bought DD a toddler bed when Target had them on sale a little while back. We got a sweet, simple white one for $75 (that was half the normal price), and she just loves it! We were able to lift her cot mattress straight out of the cot, and put it on the bed with the same sheets etc that she'd had, so that there was some familiarity to it - and she slept pretty much the same as she had been in the cot.

I never thought I would go for the toddler bed - figured I'd just buy a normal single bed and put her straight in to that when we were ready - but in the end, she started trying to climb out earlier than I expected, and the Toddler bed was a better solution for us as it fits in the same space her cot used to. By the time this next bubba is ready to go in to the cot (and therefore need the cot mattress back from DD1) it will be nearly Christmas, and we will have a better idea of how we'll fit us all in our house. lol.

I think if you get a good deal on them they're worth it - but it's hard to know. If you have the room, the option of putting the single mattress on the floor isn't a bad one if you're worried about her falling out of bed.