You can make one from a $3 stryofoam ice chest and an old lamp socket. Many have done so, including me.
Add a salvaged computer fan and a thrift store power supply and you can have a forced air incubator.
I see now that some people are even using an old electric skillet from that same thrift store, so many things are possible.
Heres the How To page here at BYC:
https://www.backyardchickens.com/LC-howto.html
Down at the bottom are 8 ideas to get you started. I also suggest you do a google search for "home made incubator." Youll get more ideas than you can shake a stick at.
I would urge you to gather your facts and understand the process BEFORE you take the plunge. If you do, you will see how easy it is.
The harder part is coming up with strong, vigorous stockf or your hatching eggs that hasnt been misbred.