Does anyone know where I can order a fairly inexpensive torque converter?

You don't. Even with the torque converter removed from the vehicle it is almost impossible to drain it completely without cutting it open though a fair amount of fluid can be removed from it.

While it is installed no fluid can be drained from it.

The converter will most likely fit on the transmission input shaft; they are fairly consistent among a brand. The issue is the diameter and depth of the converter may cause clearance issues in the transmission bell housing depending upon whether you are trying to reuse the larger or smaller of the two.

code p0703 refers to torque converter / brake switch B--circuit malfunction===causes--wiring--torque converter/ brake switch--ECM/TCM. The problem may not be in the brakes circuit but in the torque converter sensors.

I would need the actual code to give a comment. I doubt a vac leak would cause a torque converter code.

The torque converter clutch solenoid on the GM 125 transmission will stick when it gets hot and not let the torque converter clutch disengage. It has to be replaced. It is under the side cover. Quite simple to replace once the cover is off. The side cover however is fairly difficult to remove (usually involves dropping the left side of the transaxle).

the torque converter bolts to the drive plate that supports the ring gear

TCC solenoid operation depends on signals provided by the Engine Coolant Temperature (ECT) sensor, brake switch, Throttle Position (TP) sensor, Vehicle Speed Sensor (VSS) and gear position.

The lockup is the last 'shift' feeling when you get to a steady cruising speed. It basically turns the torque converter into a regular (manual type) clutch until you make a significant change in speed or throttle position, at which point it 'unlocks' and turns back into a regular torque converter. Not locking the TC will hurt your highway gas mileage, and may cause you to fail emissions testing (if you need emissions testing).

A simple loose/corroded connection can cause the error, but unless you have had work done, drivern through high water, or something along those lines, it's not hugely likely. On the other hand, it's simple, fairly quick, and the absolute cheapest thing to check for. :)

Most likely, it's either the TCC solenoid itself, or your torque converter is going bad.
Without the exact code (number) it's hard to be more exact.

There is a large chart that includes your model located at:
http://www.troublecodes.net/suzuki/
Your model starts a little over halfway down the page.

sounds like a faulty output speed sensor in trans..on driver's side of trans,screws into front of transmission..fairly inexpensive part..let me know what you find

sounds like inspection cover to trans hitting flexplate

Torque for the spark plugs is 27 ft-lbs
Firing order is 1-5-3-6-2-4