The second link only needs two bjt's (1 npn, 1 pnp) and 5x 10kOhm.
Even from the local radio shack, $8.99 for a small solderless breadboard, $6.99 for a 100' spool of solid 22awg wire, $2.99 for a 15-pack of 2n2222 npn's, $2.59 for a 15-pack of 2n3904 pnp's, $0.99 for a 5-pack of 1/8W 10kOhm@5%, and $1.99 for a female DB-9 crimp connector is only $24.54 (before any sales tax). If you can solder, you can save $7 by going with the 417-hole pre-etched PCB, and you can probably de-solder any NPN, PNP, and five 10k's from old busted electronics (dead CRT is a good example: fewer SMD's and more lead-ed/through-hole components; and for that matter, you can probably break off part of a PCB from a CRT, de-solder all the components, and use the traces already etched to save the cost of a PCB). If you have a few feet of solid 18-24AWG wire around the house, you can save $6.99; solid wire may be harder to find in small consumer electronics, but is still not hard to find in random broken appliances (and if you're soldering it, you can just use stranded wire from any random old cable or consumer device). For the DB-9, you can always chop in half any cable that plugged into a serial port (you'll need to figure which pin goes with which wire---use an ohmmeter, or if you don't have that, a voltmeter (many battery checkers are basically voltmeters) and a battery, or if you don't have that, improvise by using a flashlight with the battery cover opened (turn flashlight switch on, insert wire/pin into DB-9 hole being traced and connect to the open side of the batteries, and then try each of the wires in the cable to complete the electrical connection normally completed by the battery cover until it lights up)); it'll almost definitely have stranded wire inside, so for a solderless breadboard you'll have to use a piece of solid wire and solder them or, without solder, twist the ends together well, wrap tightly in electrical tape (duct tape can be substituted if you have no electrical tape) until of sufficient thickness, and screw into a wire cap (the kind used to connect two household internal power wires together) to keep pressure on the connection. You can forego the screw caps if you wrap very, very tightly with good tape and aren't worried about the connection holding forever.
Getting solid wire, sewing needles, or the points of safety pins to stick in the holes (not the big ones, but the small rectangular ones next to each big hole) of the OBDII connector usually works. If you don't have luck with that, you can re-bend some paper clips into a U-shape of appropriate width or use the curled end of a safety pin of appropriate size.
Really, any computer geek with patience can probably do this for zero cost ;) Even without a soldering iron, you can probably locate a section of PCB (again from CRT etc) with one NPN and one PNP BJT and without any surface-mounted components, remove other components by cutting the leads (keep in mind that longer leads might be snipped as close as possible to their component so as to create points for easy connection to wires) with wire cutters (or fingernail clippers, in a pinch), and cut unneeded traces carefully with an x-acto or razor blade (or by carefully sawing with a serrated kitchen knife, like a steak knife, in a pinch). The only part that you may have to dig around for is a cable with a female DB-9 connector at one end, and you may be able to get around that by squeezing the needed pins from the male DB-9 serial port between the insulating sheath and copper core of some wire by pushing the wire down onto the pin with small needle-nosed pliers (or tweezers in a pinch). Honestly, with a few hours and some old electronics that can be sacrificed, it's very jury-riggable, though like the parent poster states, you may need to pay a little more for decent housing and an actual OBDII plug.