I get wanting to wash your hands of Southwest credits and be done with Southwest. I am in the process of going through credits and points ASAP too. I won't be done with Southwest per se as they have 60%+ share out of my home airport, but I no longer desire to accumulate their points or credits due to the changes that are coming up.

Also I no longer trust anything Southwest says with regards to pricing and fees in the future. Potential buyers of your credits may have a similar attitude.

Another thought- do you have an employer or business who frequently uses Southwest who you may be able to sell your credits to? Especially if you are an employee of said business, that could be seamless. I've seen it done, and seen SWABIZ employees help make it happen. For instance employee of business Z gets a $400 voucher due to Southwest service failure. Employee does not like Southwest and doesn't fly it for leisure. Employee works with travel coordinator at business Z and that voucher is "sold" to business and business gives employee $400 for it, runs it through payroll as an expense reimbursement so it is not taxable (this may have been more than slightly incorrect).