Can I charge my AT7-C8 Toshiba tablet with an inexpensive USB charger instead of a Toshiba brand charger? I don't want to spend 30.00 on a USB wall charger if I don't have to. Can a cheap USB charger work to charge my AT7-C8 Toshiba tablet?
Possibly you can use a cheap charger, but it depends on the tablet as well as the charger.

Many cheap or OEM phone chargers give a low Amperage charge, from 400mA (milli amperes) to 1000mA. However, since tablets have a much larger battery, charging from a low amperage charger will cause the tablet to charge very slowly.

Most tablet USB chargers are designed to give a higher Amperage, in the range of 1000mA to 2000mA. They are generally bulkier due to the electronics needed to properly give more power. And it is also why they are more expensive.

Some tablets aren't even able to get a charge from low Amp chargers. For example, Apple's iPad will detect that you have plugged it into a charger, but it will say not charging if the charger doesn't have a high enough Amperage.

Basically, your tablet may reject cheap chargers, or it will charge very slowly. Check the mA spec of the cheap charger you are looking at; if it is below 1000mA (1A), it will likely either charge very slowly or it won't charge at all.