Strontium Carbonate is a fairly common, and relatively cheap, compound sold by pottery supply companies.
The SrCO3 can then be used as a red flame coloring agent either in its original Carbonate form, or it can be reacted with acids to produce other Strontium salts (like SrCl2 using HCl). You could also react SrCO3 with Nitric acid, providing you have any, to make Strontium Nitrate, both a flame colorant and an oxidizer in one.
Like Cesium said, Sr(NO3)2 is commonly used in road flares.
[Actually, a couple month’s back around the scene of a car accident . I started to smell something, something I recognized…I thought about it for a while and then it came to me…. “That’s the smell of Nitrates burning”, I checked, and yes, there were some Strontium Nitrate road flares which were set up by the cops.]
In my experience, Strontium Carbonate / Chloride gives more of an Orange-ish red than a red-red color in a flame. I like the reds obtained by using Lithium Carbonate (also a pottery supply).
http://www.amazingrust.com/Experiments/how_to/Images/Flame%20Test/Sr+2/Sr+2%20(SrCO3%20+%20SrCl2).jpg"
http://www.amazingrust.com/Experiments/how_to/Images/Flame%20Test/Li+/Li+1%20(LiCO3%20+%20LiCl).jpg"