Here is my $20, 10 minute flue cleaning DIY:
(3) 10' sections of 1/2" CPVC
(3) 1/2" CPVC glue to male
thread fittings
(2) 1/2" CPVC glue to female thread fittings
(1) Galvanized 1/2" to 1/4" threaded bushing
(1) Chimney brush (in my case, under $9 and 6" round wire)
And some CPVC/PVC primer and glue. If you don't have it, borrow a few dabs
Literally took about 3 minutes to put together, and less than 7 minutes to clean about
two ash buckets of creosote from the flue.
Your results may vary.