Do prints lower the value of the original? This has been debated for hundreds of years. I am about to give you my opinion.
If a collector who buys your original, sees prints of your work available at Walmart, he/she may likely think "I bought an artwork from a mediocre artist". Now let's say the print that the collector saw was in a gallery, he/she might think, "Well, atleast the artist is still prestegious with limited edition prints, but I still don't have the one of a kind like I thought I had".
I'm about to tell you - who the heck cares how many or where prints are being sold? The original will always be one-of-a-kind. There will NEVER be another original like it because IT'S the original! The Mona Lisa did not become devalued because there are millions of prints of her floating around the world - Nor did, Matisse, VanGohe, Pollock, etc.
That being said, I would sure hope that one does not have to pass away in order to ensure your original works don't become devalued because of prints.
Wether or not you make prints of your work, use your best judgement for your best interest. If you're an emerging artist like me, you might have to make prints to sell at art fairs for publicity. After all, it's not often some passerby will purchase a thousand dollar painting on the spot. Perhaps there are some of your works you'd like to make limited addition prints and others you think should stay as just the original. Make art for you, but most of all, MAKE ART.