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any benefit in trying to find a bushed chain
Very little. There might be a small gain in drivetrain life, and an even smaller gain in efficiency, but the former is negligible since the components are cheap to buy and quick to replace (cf. industrial drives where taking plant off line for an hour can cost thousands of pounds, so reducing the frequency of replacement is worth spending money on) and the latter is a concern only if you've already done everything else; it's hunting in the weeds for tenths of a Watt.
gbj_tester
Wippermann 7Z1, KMC Z-whatever, any 8-speed or less derailleur chain. If lowest price is your only concern, shop around for whatever is on offer and you'll probably get something for under a fiver.