About 6 months ago, I ordered a VFO kit using an Si570 DDS chip. The unit is self contained with a 2-line display and an optical encoder switch to change frequency down to 1 Hz resolution. If I recall the specs on the Si570, I believe it is accurate to 25ppm. It puts out 10 dBm from 3.5 - about 260 MHz. There are other models which go all the way up to 1400 MHz. I got the lowest cost unit that goes to 260 MHz, which is adequate for its intended purpose. The units are available on http://www.sdr-kits.net/
I bought it so that I can use it as a reference oscillator for various brick oscillators. I have 2 bricks in my possession, one on L band, the other on 6200 or so MHz.
Here is a test setup showing the unit in operation, referencing my L band brick: