given some 5" pipe and some flat steel you could make them yourself, which is a great idea because depending on what you want your layout height to be the height of the cup could vary a great deal.
what I mean by that is, an air spring needs to be compressed completely when the truck is "aired out", otherwise you will just lose total lift height and use much higher pressure if the air spring is not lifting from fully collapsed. there are a lot of factors that go into how tall a bag cup will be, on a clipped truck the two big ones I can think of is: 1. where the clip was installed in relation to the stock frame and 2. what diameter wheel you are using. both of these determine the spindle height when aired out.
what I would suggest is to put the truck on jackstands, take out the springs and shocks, and build a simple jig on the lower shock mount (on the control arm) of some all thread that pokes up through the upper mount. use a jack under the lower arm and lift it till the wheel is at your desired dropped height (if you are trying to lay the frame on the ground make the bottom of the wheel level with the frame, if you want to be just off the ground etc etc etc). now mark that all thread poking up through the upper shock mount.
now mark the all thread in relation to where the upper and lower spring pockets are and measure the distance between those marks, then subtract the compressed height of your desired airbag (usually right at 3 inches for an RE7 slam specialties bag) and that is the total height of your cups.
if you arent comfortable building them yourself, give your dimensions to these guys
https://www.newmaticsinc.com/Camaro-.../camr-6781.htm