I have a pair of TCXO's that would make a good stable LO oscillator for 144 to 28 MHz transverters. They are spec'ed as being 0.3 PPM but they are from China, so who knows. I breadboarded one up and it appears to be pretty good. Nice clean sine wave (most of these you see for sale are square wave oscillators). They run on 3 to 5VDC and draw about 30 mA. They are in a 4-lead 16DIP package. They are right on frequency and put out somewhere between 3 to 5 dBm - I forget how much I measured.

I was going to use these to stabilize my DEMI 144-28 transverter but decided to go with the full-blown 10 MHz reference oscillator LO instead. I paid $24USD for the pair about 9 months ago and I haven't seen them available since then. (edited) 

If you're a decent experimenter, they shouldn't be too tough to use. Data sheet (what little there is of one) and my hand drawn schematic of the proper way to couple and bypass these things will be included.

Take them off my hands for $15 (for the pair) and I'll pay shipping in USA & VE (edited)