I was trying for over a month a while back to buy size small BlackBib basic shorts but that size was constantly out of stock. I just wanted to try a pair to see what all the hub-bub was about not because I needed them, so was willing to wait. One day at about frustration week six I noticed PI Escape Quest Short on Amazon for $37 ea & free shipping so I got 2 pairs of those. I know that they are not premium PIs by any stretch of the imagination but for me they are fine. Five minutes after ordering the price went back to the normal $50 I have another pair of PI Escape shorts my daughter gave me as a gift. Those are a medium, the two new pairs are small. I wear them both, prefer the small but if they were any smaller I wouldn't be able to get them on. My waist is 31" weight 138 pounds.
canklecat speaks well about the Przewalski 3D short. I have 3 pairs size small of these in the rotation. I'm not a super critical user of bike shorts and I find little fault with these. They are my every day go-to shorts for indoor trainer use. Some of those shorts have seen a lot of saddle in the last year. I paid $19 for them a great buy in my opinion.