Velcro, nor Teflon (another popular one), came out of NASA. They were developed long before NASA was created. But for every Dollar that goes into NASA, about five comes back. I'm not sure what kind of return would be acceptable beyond that.
It also depends on what you want out of NASA and how you view the benefits. If you look for things that have come directly out of NASA and into the mainstream commerce, the return is probably one dollar for every 10 spent on NASA. But if you look at the inventions and innovations that have been spurred by NASA research, the figure can be anywhere from $5 to more than $20 for every dollar spent on NASA.
I'm not sure why people rag on NASA. During the 60's NASA's budget was 2, 3, 4 percent of the federal budget, but since the mid 70's it's been one percent or less, and it's current budget is .55% of the federal budget, a mere $17.2 billion. The DOT has a budget of $70 billion.
GPS is a DoD thing, but don't for a minute think NASA research in satellites and rockets didn't play a big part in it. Cell phones are a direct result of NASA. So it the MRI and the DVD and the smoke detector. NASA-led research on microchip technology started off for one thing, and has led to the digital camera. The entire quest to make things smaller, miniturization, came directly out of NASA. The battery powered drill that was used to take core samples of the moon advanced drills and batteries by leaps about bounds, almost of it having made it into consumer-level cordless power tools. Most of the advancement in computer graphics and error correction of data has come directly out of NASA's decoding of pictures and other data that arrives from distant satellites being carried on power that is equivalent of a feather hitting the ground.
The thermal reflective window coverings I use is the same exact material that protects the Mars Rovers, the Space Station and a large number of satellites. It was developed under direct contract for NASA.