What is the value of a 1929 US 5 dollar bill with a red seal?

Your bill should say NATIONAL CURRENCY NOTE; its seal is brown rather than red. As of 02/2015 approximate prices are:

Circulated: $30 to $200 depending on the bill's condition

Uncirculated: $100 to $3000 again depending on condition

Serial Numbers

A bill's serial number is a counter and a security feature. In most cases it doesn't affect a bill's value or help to identify it. Some collectors specialize in bills with low serial numbers (e.g. 00000005) or unusual patterns (12344321) so these can bring above-average prices.

DISCLAIMER: The values quoted are market averages as of the date shown, but may be different for an individual bill due to variations in quality and other factors. Also the wholesale (buying) price of a bill will be less than the selling (retail) price. A reputable currency dealer will be able to give a more accurate valuation based on an in-person inspection.