There are a couple of things to keep in mind here.

First, a 30" light tent is a pretty fair-sized piece of kit when set up, and there are things that are going to have to be lit predominantly from the top (top-plus-modifying-direction, at least). That means that a 12", 18" or 24" desk lamp, no matter how useful it may be otherwise, can never be more than part of the kit. That means you're going to need some sort of stand that will be at least 30" high plus some working room. The shorter the stand, the more likely it will be that you'll need some sort of boom arm to get the light where it needs to go. And if you want to do that on a tabletop, the footprint of the stand will move the light quite a ways from the light tent.

Second, portability doesn't have to mean "fits in an evening bag" or even "fits in a large laptop-type bag", but it is going to mean (probably) foregoing the cheapest options out there. The typical spun-aluminum reflectors can make the resulting package rather bulky, even if you remove the reflectors from the sockets on every tear-down and stack them. The tiny reflectors you'll sometimes see on work/utility lights (in the 4-6" range) may be good at reflecting extra light onto the subject, but they don't do much to constrain spill (the bulb usually extends beyond the reflector unless you use something in the 25-40W incandescent range).

Finally, there's an awful lot to be said for ease of set-up and tear-down, and since portability is one of your stated concerns, I have to assume that getting set up quickly once you get where you're going rather than fiddling with duct tape and coat-hanger wire to finagle things into place is going to be important as well. (It also presents a whole lot more professional appearance to clients and coworkers.)

If 'twere me, I'd be tempted to go with something like the Westcott uLite kits. (The "Erin Manning Home Studio Lighting Kit" is the same thing, but with compact fluorescent bulbs rather than 500-watt ECT-type photofloods. You can always use CFLs instead of the supplied ECTs, and there are socket splitters you can get later on to use 4 CFL bulbs for greater power.) Note that I said "something like": I know that the Westcott stands, though short, will hold out for years and will always be useful for holding reflectors, etc., when you "graduate", and that the softboxes will take more than a couple of set-ups and tear-downs without shredding, but there are some very similar kits out there for a lot less money. You can use the fixtures with or without the softboxes, and you can use the softboxes with or without the front diffuser material, so there's a lot of versatility there for different lighting styles. You can also use black fabric with a bit of velcro to mask off part of the box. And the softboxes will fold down very small, leaving the length of the folded stands and the size of the (protected) light bulbs determining the package size. You can fit the whole kit into a relatively slim and not-too-very-long tube, which will sling neatly over a shoulder.