Our toddler bed is the same size as the cot - it uses the same mattress as our cot. I got one because we had to move DD in there at 17 months so DS could move into the cot and she seemed too little for a big bed.

DD loves her toddler bed. She fell out of it a few times early on, but we put pillows on the floor where she fell out and she never hurt herself, just got a fright.

The only problem I have with them is that they are very small and DD won't last too much longer (she is quite tall for her age). That's okay thought because DS will need the toddler bed by the end of the year as DS will move into it (bit of a side issue).

Ours was $99 from Target without a mattress (mattress was about $40) both on special. All the cot linen and blankets fit it so I didn't have to buy anthing extra like that, I just used what I already had.