Retail price? Sure, but a number of large US conglomerates (the early PC era was also the height, or maybe just the tail end, of the period of big unfocussed US conglomerates) built clones in house and offered steep employee discounts across the whole conglomerate, not just the division that made and sold PCs.

As I recall, it varied. There were certainly relatively cheap Z80 and other machines like the Commodore 64. But I don't remember systems like the Apple III, Epson's machines, etc. being vastly different in price given the same floppy-only configuration.

The first "affordable" PC clones (in Europe at least) didn't appear until 1986, with the Amstrad PC1512 (apparently also marketed in the US as the PC6400): https://en.wikipedia.org/wiki/PC1512

Much earlier in the US. Most notably Compaq (founded in 1982). But many others. The one I bought in 1983 or so was from a company called Corona. I think Eagle was another.

The first (and most successful for many years) in the US was the Tandy 1000, which appeared in 1984.