What size of TV are you looking at exactly? You can get some really nice 55 inch 4K models from LG, Sharp and Vizio for around $700. If you want anything bigger, or higher end Sharp and Samsung, it all depends on the size and budget to determine if the cost / size ratio makes it worthwhile now or to wait.
Depending on your financial situation and needs, my recommendation if you really want to go 4K is get something more budget friendly now like a Vizio, which makes excellent TVs for the money, and save to get something better a couple of years down the line.