Customs on post and courier
For what its worth, I have had a lot of elctronic parts and old aircraft instruments sent in from overseas mainly by post.
My experience with post was items under $90 were rarely intercepted. If so one gets a note in the mail to pick it up from customs in the main Post office at Renon. When you go and see the customs guys they normally have not opened the delivery and an friendly explanation of what is and what is for normally gets the OK, then its passed over from the lockup unopened with out cost. Items up in the hundreds may require some skilled negotiations,the duty rate I was told was 29% but I don't remember ever made to fork out that much. Pickups are a job for an astute local, keeping the paperwork to a minimums saves on the costs.
On the other hand I have had many courier items of free electronic samples arrive by courier without issue. But ANY other item brought by a courier has been dutied at a crazy rate in Jakarta on arrival, and the couriers turn up wanting the cash and rarely have convincing supporting paperwork and rates of upto 100% declared value.
We found priority parcel post from Hong Kong, Singapore and the US all arrived within 7 to 10 days, avoided the ridiculous fees couriers charge and I'd rather nego with the customs in the Post office at Renon than take cold hits from Jakarta.
However I cant comment on what happens with printed materials or consumer goods, I have heard horror stories of expats landing goods in Surabaya also..