Have you tried to PM him? He may let you mix and match, say a couple of TO-18 with one TO-38. I bought five from him and he let me get the ones I wanted.
Sometimes it takes a few days for him to get back to you. He gets pretty busy sometimes and will get back to you as soon as he sees the PM. If you want, you can PM him again in the next day or two, if you haven't heard back by then.
Yea it is hard to just offer single modules. It is almost counter productive and don't want to set a precedent as even a three pack there is not much there but I would offer a mix match so if you wanted one of each size in a three pack or any mix you want I can do that. Other option is to get the diode in module with leads which is almost half the cost of a three pack and you get the unit ready to go.:beer:
You can buy singles in 3.8 at DTR, although you do have to purchase it with a lens other than acrylic ie G2/3E/520nm 2E. Cheapest $13 plus shipping.. there's no beating the quality of DTR modules!