Amazon is having a sale on Yost clamps which include parallel clamps. I don't have any experience with them but if someone knows their quality, they could be a pretty good deal.
https://www.amazon.com/dp/B0713YHP6Q/ref=biss_dp_t_asn (parallel clamps)
https://www.amazon.com/s/browse/ref..._m=ATVPDKIKX0DER&pf_rd_r=M9GQJ0K871QRH7JBCV3W (all clamps & vices on sale)
https://www.amazon.com/dp/B0713YHP6Q/ref=biss_dp_t_asn (parallel clamps)
https://www.amazon.com/s/browse/ref..._m=ATVPDKIKX0DER&pf_rd_r=M9GQJ0K871QRH7JBCV3W (all clamps & vices on sale)