What kind of aircraft fits your mission?
Some experimentals go together rather quickly (some completed in months, not years; e.g. Arion Lightning.)
Experimentals compared to certified aircraft of the same vintage and capability will generally take a smaller bite out of your bank account, but much more of your labor.
One experimental that has seems to have a low cost and labor while delivering reasonable carrying capacity seems to be the CH-750. Not fast and not pretty, but seems to get the job done.
That was my first question, though I phrased it differently.
If the OP needs short field capabilities and wants to fly under LSA regs, a CH-750 is one good option. If the OP needs speed and more seats or whatever, the requirements may be such that no homebuilt can meet them.
For example, if for some reason the OP wants a cantilevered high wing he wont be able to build one from any existing homebuilt designs. At least I'm not aware of any such designs.
