Low cost buck-boost (inverting) switching regulator?

[LooseJunkHater]

I'm looking for a low-cost buck-boost (inverting) switching regulator with BOTH adjustable constant-voltage (CV) and constant-current (CC) control. It needs to work down to 4v (input voltage of ~5v) with a maximum current support of 3A.

I'm thinking of going with this (https://www.aliexpress.com/item/1005006615276476.html) or this (https://www.aliexpress.com/item/1005004702899732.html) product from AliExpress, but I'm wondering if anyone has any suggestions on cheaper products? Or maybe a schematic for a DIY version that I can make? Thanks.

[kevin.gibbs]

It seems you can't find anything cheaper than on Aliexpress. The first link seems suitable. The second one's description says a minimum voltage difference of 2V. It seems to be only a step-down module.