I have never used a Keller jig or any other jig of a comparable design so consider that when reading my comments.

I know about Keller jigs and I have difficulty envisioning how you get good, accurate dovetails without a clamping system. You have to clamp the board in place some way and using F-clamps or C-clamps or any other independent clamp would, IMO, be awkward and difficult relative to a clamp made specifically for the jig. The Keller with it's clamping system will get the price up into the high $200s.

Let me suggest the Leigh Super Jig -

http://www.leighjigs.com/superjigs.php

This jig sells around $250 and it is exceptionally well made. It will do everything the Keller does plus variable spacing. The clamps on this jig are easy to use and they hold (unlike the clamps on some cheaper jigs).

You will see it pictured with the VRS attachment which is really great for capturing the dust and chips, but that is optional and not necessary to get good, clean, tight-fitting joints.

The jig comes with 3 starter bits and, for some, that is all they need. In theory, you may be able to use bits from another source, but I would advise staying with Leigh bits.

Be advised that their bits have an 8 mm shaft. The jig comes with an adaptor to convert a 1/2" collet to an 8 mm collet.

You can use a plunge router with this jig but, IMO, a fixed base router is the better option.

Spend some time at their website and check out their excellent videos.

 

I use the Keller 1500 jig for all my P.O. bank boxes. I've actually owned it for about 10 years.

It's very simple, well made, and I like the bearing guided router bit concept. You don't have to worry about the bit being exactly centered in a bit template. Amana makes a replacement set of bits for the Keller that are 1/2 the price of the Keller ones. They are available on Amazon. The bits use a 1/4" collet so there are no adapters to have to deal with. The design also allows for unlimited length dovetails even though I can't imagine ever needing that ability. I made my own clamping system. The Keller only comes with the template and bits. You have to fabricate your own mounting system and they include the instructions for doing this. You cannot pull it out of the box and start cutting dovetails. There is a little work involved to get it ready.

I would not recommend a plunge router. You want the depth of the straight and dovetail bits to match up and it would make consistency a nightmare. I cut a lot of dovetails since I am gearing up for the show season and I have two fixed base routers, one for each bit, so I don't have to go through all the changing and adjusting. This is not an issue for occasional use.

There are slicker and fancier jigs out there, and the Keller is really geared for the occasional user, but it's the one I had laying around when I started making these boxes. It works well for me.

 

I have only used a dovetail jig 1 time. It was a keller. It was simple to use , and did a good job. It might not be for everyone, but I feel it's a good place to start. It's not as versatile as others, but it costs a lot less.