I've actually sold most of the 'big' records I owned, although this was only about 15 - 20 and none was worth more than about £150, probably most in 50 - 100 region. This enabled me to buy loads of really good cheap known and semi-known + some great new sounds. I could never afford to spend £200+ on one records, I'm not staying that people shouldn't, it's all down to personal choice.
But doing this has enabled me to continue my hobby of collecting great sounding original 45's of 60's soul genre in it's loosest sense as I like R&B, club soul, hammond, northern etc.
Interesting thread, showing it's not always about the most expensive records. Having said that one of my favorite weekly pastimes is looking at Manships auctions and checking what stuff goes for!