Hi there January,
Welcome to planDisney and thank you so much for your question! My son and I built our first droid on a trip last year and had so much fun. We opted for a BB-series droid!
While there's no telling exactly what the Jawas might find while out scavenging the Dune Sea, from what I've seen,
Droid Depot typically offers accessories for your droid like colored panels, personality chips, and tool attachments. There haven't been head and leg parts from what I've seen, but it's still worth a look.
However, the accessory options available might be just what you're looking for to spruce up your R-series droid! Alternatively, maybe it's time to build a new droid friend for your existing Astromech droid. You can also check
Disneystore.com to see if there are any droids or droid accessories that might work well for what you're looking for.
Thanks so much for your question, January! I hope you have an out-of-this-world time visiting the Disneyland Resort later this month.
Have a Magical Day,
Greg