Guild Sf3’s are light, thin-line and with bigsby plus in your price range.
It depends what type of neck profile you like, as the GSF2’s generally have quite fast necks. Chet's style is usually played on a wider neck.

1999 Guild USA Starfire II - Rare All Mahogany Version - | Reverb UK

Not really a thinline but a fine guitar:

Guild X160 Rockabilly Arch-top Natural Maple Built 1999 | eBay

Or something like this but they are heavier than the SF2.

guild x170 manhatten arch top Guitar | eBay