Yes, at least in theory you can do so, although they may be a bit difficult to purchase in small amounts, especially if you want S-RECs. Wind is a bit easier to find and it tends to cost quite a bit less than solar. There are some REC marketers that have retail programs, but unlike SunJoules, virtually all these retail REC programs are just a financial transaction for a REC, without any new solar or free systems for nonprofits.
You can also consider a utility green power purchase program, where your power company sells power with RECs included as an integrated product. Just like with the SunPort, your utility still delivers power through the same wires and transformers, but the RECs are bundled in from a billing standpoint. Each program varies and most are based on entirely or majority wind power, which tends to be less expensive than solar. Also, to our knowledge, none of the utility programs include direct funding for new solar to be built.