18650 Li-ion modular battery packs
I know there are several electric formula teams running their cars with these Energus modules, so I guess it is worth the money. I am thinking of these modules myself, following the company for some time now, but did not yet commit to buy.
If you are novice with lithium cells, it is better to buy than to do yourself, it will be cheaper in the end. Just make sure yiu use a good BMS, that yiu can trus your home with. Energus offers that as well, if your are not going above 60V nominal.