I started offering a 10% discount to all non-profit organizations plus some very large software license discounts if you happen to be using the Microsoft Dynamics RMS point of sale software. You can reach me at 2208-340-5632 or email@example.com for more information (and references as well).
A quick note that I have a great deal of experience providing in depth (but unbiased) point of sale consulting services for Goodwill stores. This also applies to thrift stores in general. As this normally involves some travel, there are some fees involved (unless you are only in need of some general advice which is free) but the outcome is solid recommendation of the next steps your organization should take.
Here are some videos that highlight my processes for in depth consulting. As always, visit my contact page to learn more and to see whether I can help you chart the best course for point of sale, warehouse management and/or inventory control software and systems.