Mk 1s come around less often, but are generally less expensive than Mk 2s, however, the 38mm watches seem to be gaining in popularity, as the fashion for larger watches wanes.
A word of caution if considering swapping movements, cases or bezels to achieve your goals, the parts might seem like identical and interchangeable parts, but this is not the case and you can easily come unstuck, or literally stuck, if you happen to pick a mismatched bezel size.
Best option for a red/black auto combo, is to pick up a reasonably common Mk1 in black and an all red model, swap bezels and move on the combo that you don't want.
For info, mine is a one off. I very much doubt you will ever see another, unless someone goes to a lot of trouble.