Does anyone have any rough estimates what it'd cost to ship a bare 2L case? Shipping distance would be about 300 miles.

It can ship UPS, You will need the actual box size and the zip code, be sure to insure it, UPS insurance is CHEAP..use it!!
I'll bet you can ship it for around $20.00 +-

I shipped a bare case from CT to West Coast CA used Fedex ground was about $35.
I put it in a large Suit Case Box. Head studs were removed to save room and aviod poking through the box

I just sent a set of heads to RIMCO from NH.....$23.00..

Thanks for the answers guys. Now if only I could get the guy selling the case to ship it, instead of me driving 550 miles round trip to pick it up.