I'm currently using a set of weedwhacker synthetic gut strings that I got off eBay. Having been a user of gut strings for many years, I was amazed to find that these (for me, anyway,) behave like a good set of guts but without the string prep needed for Arco, not only that, but as they're synthetic theY're not affected by changes in temp and humidity.
I'll be staying with these strings, I mean at about £45.00 a set compared with the £150 - £200 a set for guts it puts a lot of pennies back in my pocket