I went back and forth for ages changing my mind about the kind of bed to get for DD. In the end, we paid about $700 for a double white timber one from 40 Winks.
It has two heights, a footend (DD still moves about a bit and it saves her falling off the end), is good quality (so hopefully will last until she wants to buy her own), can double as a guest bed if needed, and can fit a fat, pregnant/breastfeeding mum for story time or night cuddles if necessary.
If you'd have asked me a year ago if I would buy my toddler a double bed, I would have thought you were crazy. But I am super happy - it's working really well in all ways for us.