Will they charge import taxes on checked baggage stuff? etc

The $500 exemption applies to everyone coming into CR.  We have brought in vitamins and OTC meds without any problem, but there are no guarantees in CR.  If they are not in excessive quantities and are considered to be for personal use, it likely won't be  problem.  If bringing a number of bottles, distribute the bottles in your luggage so they are not all in one place.

The $500 applies to residents. Non residents may bring in many small items as long as they are not commercial goods to be sold in CR. A very clear description of what is permited for non residents or tourist is listed in English on the ADUANA FORM (NOT THE IMMIGATION FORM). tHESE MUST BE THINGS THAT YOU WILL PERSONALLY USE WHILE IN CR.  Even a small tv is permissable but it must be small. When you get your baggage be sure to go through the nearest xray baggage check and give them your ADUANA FORM BEFORE THE BAGS ARE XRAYED. PC is ok even if you have 2 but if you bring in anything that is in its original package you may find yourself subject to scrutiny.  Be sure to tell them if asked that everything is for your personal use while in CR.

Not so. The $500 waiver is for everyone...as is the rule that they are not bring in commercial goods to be sold in CR be they residents or tourists.

Kohlerias is correct.  That is why you fill out the declaration form to that effect when you fly into Costa Rica and when you do a 90 day border run.

Thanks for these replies. Good to know the rules and also how things really work in the real world here, which are often 2 different things.

My wife was in the US and I ordered about $700 worth of stuff for her to bring back - stuff that is too expensive to get here, too low quality to get here, or just unavailable here. A LOT of stuff falls into these 3 categories, as far as we're concerned. But that's another thread...

Anyway she got in with no problems, they didn't even check her bags really. She took everything out of commercial packaging although one could still see it was new stuff if one looked - but no real proof of such. She brought in seeds, vitamins, herbs, electronics, clothing, all kinds of stuff for us. No problems. Recently a friend of mine also brought stuff in, in a bag I had left with him. Water filter, vitamins, art, misc. stuff... They also didn't check his bags.

They DID check our bags when we moved here last year with 5 duffel bags and 2 carry ons. However they checked "loosely" and did not question us and let us through, no problem. My wife said they checked some people in front of her who had 5-6 bags this time.

I do not know as a fact, but I understand that US$1,000 may be brought in without attracting tax.  Yo may wish to check this out.

As an update to this question, I recently went to the USA and brought back 2 duffel bags full of new stuff and old stuff for our household - clothes, vitamins, sculptures, paintings, towel and clothes racks, even vege and flower seeds, etc etc. and the border guys didn't even open them, just waved me through. When I went through this time I saw them waving everyone through.
I think they were tired as there were like 1000 people going through customs when I went through - the most I've ever seen - that huge room was FULL.

Anyway based on my wife's and I's experience if you take new stuff out of the box so it doesn't look so new and go through customs with a smile and a good attitude, no one hassles you. I think taking stuff out of the boxes so it doesn't look like new is a major key to all this; but who knows maybe they just don't give a dang  most of the time, anyway...?

Of course, your mileage may vary...