The most expensive choice is of course the Genuine Swiss Army replacement band. Please note eBay sellers are supposed to put "Fits" or "For" in the title of Swiss Army Bands which are not genuine Swiss Army. The occasional seller might miss it, so be sure to double check the sellers description to be sure who exactly made your band.
Currently in the the top replacement band manufacturers are Hadley Roma and Speidel. These are top notch replacement band companies who are still in business and who will cover their bands under limited warrantee for manufacturing defects if the product is purchased from an authorized dealer. Other watch band companies such as Kreisler are no longer in business, so obviously they will not cover their products. There are authorized dealers selling bands on eBay so be sure to look out for them. Always ask your seller questions if you are not sure about the product.
Product Sizing -
Width: The size band you need is measured as "Lug Size" which is the width in mm's of the band where it meets the watch. Some bands are stepped and are a bit wider slightly farther down the band away from the watch. What we want is the width of the band where it is meeting the watch. For instance typical men’s sizes are 16mm, 18mm, 19mm, and 20mm.
Length: Length is a bit tougher to determine. Hadley Roma and Speidel BOTH offer Long lengths in some colors and sizes (But not all). To properly determine length needed:
Measure wrist (For instance 7 1/2")
Add 1/4" for comfort (Our example now 7 3/4")
Subtract the length of your watch when looking at it with 12 O'clock facing up (For our example let's use: 1 1/2" so now 7 3/4" minus 1 1/2" = 6 1/4")
You now know what length at which your band needs to fit. In our example we need our band to have a hole somewhere near 6 1/4" for the band to fit correctly. A typical Swiss Army men’s band is 8" INCLUDING buckle. Generally the last hole is within 1"of the end of the band. So if we need a hole at 6 1/2" of band we are safely before the last hole, and would be able to wear a regular band. The terms regular and long are relative in the watch band world, be sure to check the listing for each item you are interested in for the exact length of the band, so you know what you are getting will work. In general the last hole (so the biggest size the band will fit it is always at about 1" from the band's end)