Since boom-boom is not your thing and looks like space is priority then 2 sub enclosure is out of the equation na. Probably a sealed enclosure?
Your amp is 100x4 rms and kahit bridge pa ang 2 channels kapos parin sa rating ng sub not to mention 4ohm lang and your sub is dual 4ohm so either 2 or 8ohm lang option dyan. Meaning need mo ng dedicated mono amp.
10k for seps, enclosure i think kasya if you get some jbl or infinity seps and ctk deadeners. But if isama ang labor baka mabitin ang 10k na budget mo but I might be wrong about sa cost of labor dahil puro lang ako DIY

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