Why buy radials? They're just wire. Do you mean you have to buy the wire?
If the 6BTV is installed at ground level, thirty radials 25' long each work well. That's 750 feet of wire. If it's elevated, four radials cut to 1/4-wavelength each per band (x5 bands = 20 radials) works well; that takes about 550 feet of wire (you can use the 40m radials on 15m).
Either way, it's just wire. Elevated radials should also have end insulators and tie-off ropes to be sure the radial ends don't contact anything. On the ground, the radials can lay on the ground or be buried slightly beneath it and no insulators are required.
What if soy milk is just regular milk introducing itself in Spanish?