Hi Rosemary,
I know ALL CAPS have been known to hurt CTR. If I am searching google and I see a title tag or meta description with phrases in all caps like CHEAP, BUY HERE, etc., I tend to lean toward the opinion of thinking the content is spammy and click on something that looks a bit more professional.
Also, take a look at Googles product search editorial guidelines here. https://support.google.com/manufacturers/answer/6124110?hl=en
In it they state, "Avoid any repeated and unnecessary use of punctuation, capitalization or symbols. Don't use exclamation points in your product titles. The use of symbols, numbers, and letters should adhere to the true meaning of the symbol."
I would err on the side of caution purely because CAPS can hurt CTR. I don't think there is a consensus on whether or not CAPS can help/hurt your ranking in the SERPs (there has been evidence that suggests both) from an SEO perspective.
Hope that helps!