I need a bit of advice...

I have a domain I want to use to promote a CPA offer but at the same time I think it will make a great site in the near future. 135,000 monthly keyword searches low competition. Should I just buy a similar domain for the CPA offer? I don't want to get out there promoting it after I have been sending people to another site and it doesn't get as much interest when Im ready to turn it into my own thing. I don't have the $700 disposable right now to get my own site going like I want it.