You know, it takes a little patience, but I have found a variety of vests on eBay that I use for concealment. Almost all have some pockets and unlike many folks who wear pocketed vests (photo, adventure, or whatever you call them), I use my pockets to actually carry things. That is why vests seem to scream that the person wearing it isn't wearing it out of any practical reason other than for concealment. And with kids, those vests are a great replacement for a diaper bag when out and about. I can carry diapers, changing gear, bottles, and snacks for all day long, as well as concealing a full sized 1911 and associated spare mags! Okay, so there is little that can conceal the bulge of a gun like a couple of thicknesses of diapers!
Seriously, you can find some neat stuff on eBay, but you need to be aggressive in your searches. I have also gotten some neat vests without pockets that work really well. Here are some terms to consider using in your searches...for all types of vests...
photo vest
photographer's vest
photographers vest
journalist vest
hiking vest
cargo vest
adventure vest
bird vest
safari vest
travel vest
orvis vest
cabella's vest
(any other brand name and the word 'vest')
gear vest
Banana Republic vest (not all look like photo vests - they have had a variety of styles over the years)
Mexican vest (some colorful designs in interesting weaves that do well for concealment...but you look like a tourist!)
race vest
game vest
event vest (these three pertain to flashy vests given to photographers for various sporting events and do not usually have pockets, but do have the event name in big letters. These look like souveniers from the event. Some work well for concealment).
You can search by material as well. I have a couple of heavier vests that I found by searching for 'canvas vest' but you can also search with words like leather or cotton.
Other ways to look for vest are to look for product endorsement vests. For example, there are a variety of leather, canvas, and cotton vests for Harley motorcycles, some of which scream Harley and some that just have a tiny logo. I have a Harvey vest (inside vest pockets only) in maroon that is only identified as Harley by the zipper pull and by the label insde.
Searches can be narrowed by choosing a sex or size.
If you are creative in your searches, then you can compensate for the lack of creativity on the parts of some sellers. Also, by getting a couple of different styles of vests in different colors, it just makes the vests look like you wear them as a regular accessory to your wardrobe.