So for installing over concrete you’ll need to have a vapor barrier and 3/4” OSB installed over top. Figure around $1.50/sqft in materials, if you buy them at Home Depot.

Subfloor install might be around $500 or around $1/sqft Hardwood floor install probably would be $1000-$1500, around $2-$3/sqft, so maybe $1500-$2000 for install.

Assuming $5/sqft for the flooring, plus subfloor you’re at around $3250 in materials.

I would try to get a labor only quote, reimburse them for subfloor expenses and source the flooring yourself to avoid getting a markup on the materials.