If you really want it as cheap as possible, - buy the cheapest 12V panel. Then add the cheapest 10A controller from Ebay, Amazon, Aliexpress, Bangood etc. Sometimes cheap controller is bundled with panel. Add any cable #10, crimp some disconnects on it. Will work. Performance and reliability is different story. If controller goes bad or doesn't work well from the beginning or can't be set up as per your battery specs, - it will shorten your battery life, so keep an eye on voltage.
Monocrystalline is not better than Poly.