Hello,

> I'd like to know where to find a curing oven and how much does it costs.
> I imagine that they are very expensive.

If you buy new, yes, they are quite pricey. Even on Ebay and other auction sites for used lab equipment you have to expect to pay a lot of money.
I have found suitable old laboratory heating cabinets by dumpster diving at the local university and other research institutions. Non-functional ones could have been repaired relatively easily.

> Is there a more economical solution to make carbon parts with pre pregs?

Yes. Build your own. A well insulated sheet metal box, a fan and heating elements from household ovens, a good solid state relais, a suitable PID controller and a temperature sensor from Ebay will get you started.
For small parts even an old kitchen oven can be modified to work satisfactorily by replacing the temperature regulator. Unmodified ovens have a terrible temperature swing and are very inaccurate, use suitable electronics (PID controller) and temperature sensors to tighten this up.