I use Maxi-Cure extra thick (10-25 sec. set) CA. I buy it in 2oz. bottles. You can find it at most hobby retailers, but you'll want to look at the "local" or "mom & pop" type hobby shops.
Here's a pic:
Here's a link to the website for the producer, BSI adhesives:
https://www.bsiadhesives.com/Pages/hobby/ca.html
In the pic, you'll notice that there is a silver rectangle with the BSI logo at the top of the front label. When you find it in your local hobby shop, this BSI logo will most likely be replaced with the logo of that hobby shop (the bottle I'm using now has a "Wild Bill's Hobbies" logo on it, and my spare bottle has a "HobbyTown USA" logo in that spot.)
The stuff retails for about $8 for a 2oz. bottle.
I prefer the extra thick CA's with the longer set time. This allows me to lay it on thick when applying fins (apply to the root edge of the fin itself), then set and position the fin. Provides a tad of workability so you can position the fin correctly, then dries very quickly and provides a super, super bond.
I've used several other brands of thick CA, including Slow-Jet and Pacer Slo-Zap. The Pacer Slo-Zap runs a close second to this BSI stuff, but the tip and applicator are difficult to deal with. For overall performance, this BSI CA is absolutely my recommendation. I use it almost exclusively in my builds: fin attachment, motor mount assembly, motor mount installation, couplers, you name it. I only use epoxy where there is somewhat of a "loose" fit when installing a motor mount or a coupler or something.
Bottom line: check out your local hobby retailer. They're sure to have something that will fit your needs.