Graham Sutherland / PolynomialLCSC should do a thing where you can put a bunch of stuff in your basket, then link it to a JLC order as a parts consignment, so your parts and boards all get get bundled together and you save on shipping costs.
Sconient@gsuberland they kind of do that already. If you place a PCB order, then a parts order, there's an option to waive the shipping cost of the parts order. They still get shipped separately though.
At least they did that the last time I made an order. They may change that policy at any time...