MIght be too late to chime in here, but I've the perspective of making all dovetail joints in my shop by hand. I have an Incra router table system, but after making a few boxes with it I decided that the "dovetail within a dovetail" that it will make was a bit too kitschy for my taste, and the standard dovetails that it will make don't meet my aesthetic requirements - they are too uniform and blocky.
I've also the perspective of teaching a few folks to cut dovetails by hand, so I've seen quite a few of the inexpensive "dovetail" saws from the big-box stores. The following is my opinion only:
"Dovetail" saws from the big-box stores are mislabeled. They'll cut wood, of course, but are an incredibly poor choice for someone trying to learn to do this by hand. They are often filed cross-cut with a high degree of set. While one can use a rip saw to make decent cross cuts (it'll just be slower), the opposite is not true. The chisel-point of a cross-cut tooth wants to follow grain lines, with the result that it's difficult to track a cross-cut filed saw when making a rip cut. The high degree of set is really, really bad for cutting dovetails. Because the set determines the kerf width, and the set is so much greater than the saw plate thickness, the saw wants to wobble in the cut, which is a disaster when hand-cutting dovetail joints. When cutting the first part of the joint (either tails or pins), it doesn't matter whether you track perfectly to your layout line, but it's critical that you be able to make a straight cut - any curve or correction in the kerf will make it nearly impossible to layout the opposite side of the joint and cut it so that it fits correctly.
The performance of these saws can be corrected to a degree - one can re-file the teeth with a 4" extra double slim taper saw file to remove the bevels on the teeth, and you can stone the sides of the saw or use a brass hammer and a wood block to remove some of the set, but this needs to be done correctly, and most beginners will not have the skill nor know how to evaluate the results of the tuning operation.
So for that reason, I highly suggest that you save the pennies necessary to either buy a Lie-Nielsen, Veritas, Adria, Wenzloff, Medallion Toolworks, Rob Cosman, or Andrew Lunn saw. All of these saws are correctly set up to cut dovetails out of the box, and when you're learning to do this, throwing in the extra difficulty of having a saw that is more difficult to use may well result in giving up in frustration.
Another alternative is to purchase an antique Disston, Spear and Jackson, Atkins and Son, or one of the numerous other 19th century British sawmaker's saws and have it correctly sharpened and set. Technoprimitives is one service, and there are other individuals out there that will do this for you for a reasonable charge. However, once you fight the collectors for a saw in an auction and then send it off to get it correctly set up, you may not save much money over a Lie-Nielsen, and definitely not over Lee Valley's inexpensive high-tech backsaw.
The handle on a dovetail saw is also very important, because your grip on the saw will sensitively affect the results. It's for this reason that I don't recommend the slightly higher-tier but still very cheap saws from Lynx, Pax, or Crown unless you've the tools, desire, and skill to modify the handle to remove the sharp arrises and make it fit your hand better.
Also remember that you are likely buying a dovetail saw for life. You would have to build an enormous amount of furniture to use up a high-quality dovetail saw by re-sharpening and re-setting the teeth. From that perspective, spending $120 or so on a saw that can be handed down to your grandkids doesn't seem so bad.
Finally, be aware that, particularly with Lie-Nielsen products, you can get back 80% or more of your initial investment if you decide hand-cut dovetails are not for you and want to sell it.