I see two problems though. The biggest one is that hardware vendors are starting to add cryptographic signatures to their firmware upgrade process.
And another problem is that the hardware often has very limited memory, which makes it impractical for many things.
serial console/TFTP/buy from vendors that don't restrict your choice (ubiquiti, netgear, belkin/linksys, some chinavendors come to mind)
RAM is usually fine, just get a decently specced router.
I see two problems though. The biggest one is that hardware vendors are starting to add cryptographic signatures to their firmware upgrade process.
And another problem is that the hardware often has very limited memory, which makes it impractical for many things.