I have serious doubts that the clock source can be voltage leveled and still BE a clock source.
ARM chips run at 3.3V but the slowest I know of run at 48MHz.
But hey! An AVR at 3.3V with a rock-steady clock (resonators can be off minutes per day) isn't a bad thing. They use less power especially if you don't include a USB chip and some other bits found on Uno and Nano boards.
If you are only hobbying it is cheap to build using DIP chips on protoboard, not sure what route you take with surface mount but I've seen boards for some of those at DIPMicro and around. I have seen boards to give DIP-format pins to surface mount chips.
The DIP ATmega328P-PU cost just over $2 for 1 last I saw on Mouser.I call that cheap.
Looking for breakout for your TCX0, which one you have makes a difference. I can't tell which links to show.
Considering what these modules are for, I don't expect cheap and I do expect them to be used with automotive AVRs in hot environments. This is as deep in the topic as I care to get.