That very much depends on the country you're in: @boonhet@sopuli.xyz found them at €0.13/watt sold to consumers in Estonia, which is an EU country which has 0% VAT on solar panels whilst the EU itself has 0% Duty Tax (aka tariffs) so there is no tax at all on them and their price is just factory price in China + shipping costs (probably by ship, which isn't actually that much when shipping full container loads of them) + profit margin for importers and sellers.

Even in the US, given that Duty Tax if applied to Purchase Price + Shipping Costs To US Border, if the purchase price of the panels goes down, the price in the US after Duty Tax will go down, though it's ultimatelly bound by Shipping Costs To US Border (which aren't actually all that much if shipping full container loads of them from Shenzheng by boat). The point being that the Duty Tax for solar panels would have to be many 100s or percent for them to never be lower than $0.35/watt when factory prices in China are already below $0.12/watt.

I think that the reason for US prices is all the intermediaries adding their margins on top of the base product price.