Specialist micro-engraver Graham Short has said he spent the money featuring his work at a cafe in Blackwood.
The artist saw his note was not checked by the cashier and hopes it has ended up as someone`s change.
The other notes were spent in England, Scotland and Northern Ireland.
Mr Short came up with the idea of engraving a 5mm portrait of the Pride and Prejudice author on the transparent part of the new plastic Bank of England £5 notes, to mark the 200th anniversary of her death next year.
He has included a different quote around each one, ensuring each note is unique.
Mr Short`s last work, a portrait of the Queen on a pinhead, sold for £100,000.
"I`m fortunate that my work sells in the world`s top art galleries to fine art investors," Mr Short told BBC Radio Wales` Jason Mohammad programme.
"Generally this artwork is out of the reach for most people. I wanted an ordinary man or woman to find it in their hands.
"I didn`t spend the money in somewhere like Harrods or an expensive restaurant. I bought a sausage and egg sandwich in a high street cafe.
"I chose Blackwood because that`s where my mother was born in 1909."
Mr Short described his sandwich at Square Cafe as "good" and said it was bought at 14:30 GMT on Thursday, 8 December.
He added: "I was hoping that the lady wouldn`t check it when I gave it to her - which she didn`t - because I wanted it to go into somebody`s change.
"I don`t know how far the note will travel. It could be local and I hope it is."
Mr Short said his work usually sells for about £100,000 and the notes were insured for £50,000 each.
"I would hope they put them on to an internet auction site and I would hope they could get some money for Christmas," he added.
Jane Austen £5 note `worth £50,000` spent in Blackwood
14 December 2016
Read: 1464
One of four special £5 notes engraved with a tiny portrait of author Jane Austen has been spent in Caerphilly county and could be worth up to £50,000.
