Don't buy anything for a heavy yet. Build something small n get used to it all first The main problem with the smaller controllers is that they get hot. Even though there are small controllers with the amps rating, a small plastic box cannot dissipate the heat a big meaty dual controller can. Buying four small controllers divided between two big motors will be a nightmare to cable and set up.

I may get moaned at for costing someone a sale but £180 would nearly buy you a good quality dual controller. I am by no means an experienced robot builder, but I am an experienced electronics technician by trade. Please message me if you need any help and ask questions before you spend money.