AD 2008-13-17 does allow for an alternate means of compliance. Basically, you apply for using a different CB Switch. This applicatrion, with loads of supporting data, should be processed through your local FSDO to the Manager of the Wichita Aircraft Certification Office.
Don't have your hope too high, they may or may not approve it. On your side, however, is not making the issue of parts cost, rather the fact your Bo is relegated to Day VFR.