your budget, something enjoyable until you save more money and get lucky with a great speaker find. IOW, you will upgrade, so get listening pronto, the speakers the most important, let features help you choose electronics.
USED yes, and LOCAL. you need to find something you can drive to pick up, either go there, listen 1st, or meet seller half-way.
where do you live?
One thought is to search for ’stereo system’, find one with speakers you want to use for a while, the electronics more than likely pretty good, easy to sell/trade/change separately later,
suppose you lived in Canada, I’d be borrowing a truck in case those Polk speakers sound good, get the R2R ......
Complete System, Canada, $1,300 USD.
Of course look for only speakers, only integrated separates, vintage receiver: it’s just that sometimes people selling complete systems are in a hurry, don’t know what they have, need money ...... you might get lucky
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Near these KEFs in the UK?