my impression is that most CL these days is existing large closed-source codebases, hence the price tag for those compilers (you're not trying it out for a bit,

my impression is that most CL these days is existing large closed-source codebases, hence the price tag for those compilers (you're not trying it out for a bit, you're funding the compiler devs to work full-time on the issues you're actually having) and relatively little open-source activity for "finished" things -- if you're developing against internal libraries, it's hard to open-source just the part you intend to (work at a CL shop; mostly SBCL users, but maybe 1/3 of people are die-hard ACL fans)