In most places that sell backpacking/camping supplies you can buy an orange plastic trowel for $2-3.

If $2-3 is not low budget enough for you, Fiskars makes a transplanting trowel that is black with an orange tip on the handle. To me it seems to be just a little stronger with a bit more comfortable handle than the typical orange plastic backpacker trowel. I have been using one in my pack for the past few years. You can usually find them in the garden section of your local whateverMart type store. Price is about $1. I just picked up a spare at the local drug store as end of season clearance for 50 cents. (Wife cannot complain much about a new peice of gear that costs less than $1.)

I have used one for a few years in the garden for it's intended purpose. Works well for that too.

They are 11 inches long and weigh 2.9 oz on my postal scales. The orange backpacker plastic trowels are 11 inches and around 2 oz.

Anyway, it is a great low-budget piece of gear. If you just have to have a new bit of gear and only have pocket change, check out the garden supplies. Lots of that stuff is going on sale this time of the year.