desert species and sources for seeds

So what are great/good/excellent species for someone heading out to a arid/semi-arid climate?
I've been creating lists [species & arid climate gardening] but that's mainly about raw data. There's also
- what seeds can be had (internationally) online?
- edible?
- guilds?
- resistant to local livestock
- good for creating or improving soil
etc.

I'm heading to Morocco, i.e. comparable to Texas or Mexico (depending on where in Morocco i wind up).
There's also the matter of ordering seeds; often retailers in the U.S. won't ship abroad or will demand payment by credit card. Both are deal breakers for me unfortunately. The best is a Paypal option and that's why Ebay is my go-to source, but they often don't have what i want.

Good sources? Ideas? Lists?

For me, I eventually determined that great/good/excellent species for my arid climate are those species that are already growing in the area, regardless of their provenance. (I don't care if they are endemic or if they traveled. The research is too hard to do anyway... Even identifying one plant/animal can be extremely time consuming.)

A common strategy for me, it to collect propagules from up to 150 miles away growing in similar conditions, and grow them for one to four years in pots in a nursery to get good root systems established, and then plant them back out into the desert when conditions seem favorable... (For example, if monsoonal rains are expected). Also I put them into micro-climates that are suitable... For example, right where rainwater pours from the face of a boulder, or on a berm or swale that captures sheet runoff.

I'm working on domesticating a few species... Selecting for less bitterness, better agronomic properties, larger leaves, more vigorous growth, etc...