This is a list of parts I discussed for my new telescope setup and these are the four places I usually check to see if anyone has them in stock.

https://optcorp.com/
https://www.highpointscientific.com/
https://agenaastro.com/
https://telescopes.net/

William Optics
RedCat 51 APO 250mm f/4.9

OPT - The Telescope Authority
Radian Telescopes 14-inch Lightweight Universal D-Style Dovetail Bar

Pegasus Astro
Pocket Powerbox Advance

Strenco
2 Inch Hook and Loop Strips with Adhesive

ZWO
Standard Electronic Automatic Focuser - 5V USB Version - EAF-5V

SmartComponents on Etsy, Nikolay Ivanov
EAF focuser mount for RedCat 51 and SpaceCat
https://www.etsy.com/listing/11638714...

ZWO
ZWO ASI120MM-S Monochrome CMOS Astrophotography Camera

ZWO
ZWO 30 mm f/4 Mini Guide Scope

ZWO
ZWO EFW (8 x 1.25" / 31mm)

ZWO
ASI1600MM Pro (mono)