The ER collet system is very adaptable and you can go from extra cheap to super precision depending (mostly) on the collets and nut you choose. If you bought something like the Shars unit I posted you could cut it down to fit snug against your existing collet and pretty much leave it in place while you look for a set of the 2E collets on eBay.
ER chucks are available from all major suppliers as well as Amazon, Banggood, AliExpress, etc.
John