How about Forestfarm? They have amazing selection of Lilacs. I did not see Pocahontas there, but they have 'Beauty of Moscow' ('Krasavitsa Moskvy') and several yellow ones ('Beijing Gold'). They have excellent reputation for the quality of their plants. Their prices are very reasonable.
I ordered 'Josee' (the only reblooming Lilac) and 'Nadezhda' for this fall delivery from them.
Lilacs at Forestfarm

I thought about them, but they charge an arm and a leg for shipping.

I paid $41.70 for the shipping of 10 shrubs. Did you see lower shipping cost somewhere? Songsparrow has nice choice of Lilacs, but if you do not like Forestfarm's shipment charges, do not waste your time looking at Songsparrow's Lilacs. Bluestone Perennials has cheap shipping, but their shrubs are tiny, it takes forever for them to grow.

Our local Costco had Lilacs last spring. Maybe, you should look for your Lilacs locally? 'Beauty of Moscow' is definitely very common.

i say this because if i were to order from them, i'd be only ordering a couple lilacs, not several, which would make having them shipped expensive, unless of course by the time spring comes i'll have other plants on my list...lol. I'll prolly hit the locals in the spring first, but just wanted opinions if i can't find what i want locally to get it from an online nursery.