Thinking of Growing Capers in Southern Spain

I have purchased some land in Southern Catalunya, which is in full sun almost all day, but is sandwiched between two rice fields. The soil is clay like, and quite moist, as it has not been roto-tilled for some time. I'd like to plant something on this land as it is lying idle. Local people have suggested orange trees or olives, but I am quite drawn to caper bush, as there seems to be an abundance of olives and oranges trees in the area already.
My question is, will caper bush thrive here, and where can I purchase some saplings or seeds of the caper plant?

The soil as you describe it is not ideal for caper bushes. They like well-drained, sandy soil and, once established, tolerate a fair amount of drought. But you might have to plant the bushes on mounds to get the required drainage.
Richters sells the seeds but seeds are slow and intermittent in their germination. They should be packed in moist sand and frozen for two weeks before sowing. Likely the best approach is to start mother plants from seeds and then take cuttings from those mother plants in order to expand your planting to your desired plantation size.