I actually think this is a great idea as contamination with allergens in spices has happened and more than once.
First question you might want to answer is risk of cross reactivity on those strips. I'd get some advice on that. Also do you then follow up any positives with ELISA to confirm?
But my second question may make you rethink (or may make any of your customers furious with you). What will you do with the results?
Now I actually hate myself for asking this question because it's all about business protection and NOT about food safety. But in the UK we have a retailer called M&S and they do not let you test ANYTHING for allergens (ingredient or product) unless it's in your control AND you have their approval. Why? Because it might not impact only your company.
Think about it. You have a delivery of ground cumin for example. That same batch is also delivered to a meals manufacturer, a spice paste company, a fast food restaurant, the sandwich supplier etc etc. You find peanut protein in it. Imagine the size and impact of recall... Ooh I feel dirty talking about commercial considerations. 
That's why I hate myself because if it's there I don't actually care how much money is wasted. BUT if you trust your supplier, would it be better if they did the testing before any of that batch left their control?
Or if we flip this on its head, TELL your supplier you're going to start doing this testing at intake and I guarantee they will start testing every batch before it leaves their control because of the implications.
Ok I've talked myself back into it. Crack on but make sure everyone knows then on their head be it! 
Answered
