Eh mak, those prices are reasonable lah, especially if new condition! I'd say go with the RM30 one first since bengkung is very personal, some mums swear by it for postpartum recovery, but honestly a few of us tried and didn't feel much difference, so worth testing at lower price first before committing more. Just make sure got instructions on how to tie/zip properly, that's the key!
Aa_H