Alternative to (subwoofer) BOA 300 AK ?

Hi, my self-constructed Emphaser/Axton-unclean-playing bass reflex subwoofer is now (juhu) on sale, I have 2 interested parties and one of them wants to have it in any case (80€). So, some time ago I listened around here which is for little money OK and then decided for the Axton CAW-305. But I was also recommended the BOA 300 AK as a complete box, does not cost much (ebay around 110€) and should be quite good (hallo altas ). But my thoughts are now: these are 110 € for a new subwoofer ! I can definitely find a “better” used one, or not ? Should definitely be a 30cm bass reflex, for Hip Hop and R’n’B. I could also make self-building, but I rather shy back because I have little time/destination and that then becomes with the spanning and something like that again … So either n complete subby or an eBay box with a good woofer in the price frame up to 110€. Is once again not much, but as a student without a side job, which also I don’t know how much I can afford to pay for repertures. Oh yes, power amplifier is not yet fixed. At the moment everything is being sold out profitably, wants to see if it becomes a 4-channel or a mono and a 2-channel… but at least 150 Watt RMS will be there for the sub. Well, let’s say 200 Watt RMS. Hope for interesting suggestions ms