>>You can probably get like brumuda (sp?) grass seed and timothy seeds from a garden or feed store. Just look up a few good grasses and then call around and see if anyone carries them. It would probably be much cheaper that way.
It's spelled Bermuda. 
I've never lived anywhere that I can remember where Bermuda didn't grow everywhere on it's own with no care.
As an adult I learned that in some regions it's considered a weed grass. lol
I think though that whatever type of grass you want to grow, you'll have to make sure that your region will support it.
For example where I live some people want to have St. Augustine grass for their lawns but it's extremely difficult to get that to grow here. People do it but I've known plenty of people who gave it up because it just dried up & died. It had cost them a lot of money which was wasted.
The Tortoise Trust website has a list of grasses that are good for sulcata tortoises and I would think if you compared their list to a zone list like this one:
http://www.seedland.com/Merchant/merchant.mv?Screen=SFNT&Store_Code=Seedland
you could probably find a mix that would work for you & your tortoise.
Buffalo grass is on the Tortoise Trust list of good grasses, we looked into that for our lawn and OMG the price for that type of seed here is sky high. We already have the Bermuda so we just stuck with that.
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PHRatz