Does anyone know where I can buy a THIN necktie?

Answers:
At most stores that sell ties :-)

OK, seriously now, try men's specialty stores in your area, they are more likely to have the different style ties. If you can't find any, then look on line. Everywhere from eBay to Amazon to Overstock will have them. They are just now coming back in style, so it may take local stores longer to get them in stock than it does the on line retailers. When you do a search, remember to try all possible words, skinny, narrow, thin, slender, etc. You never know how it will be listed.
http://clothing.listings.ebay.com/neckwe.
http://www.overstock.com/cgi-bin/d2.cgi?.
http://www.amazon.com/b/ref=sc_bm_l_1_10.
http://www.menswearhouse.com/menswear/br.

If you have any in your area, or want to look on line, there are men's accessory stores. They sell nothing but ties, scarves, wallets, cuff links, etc.
http://www.wildties.com/;jsessionid=cioi.
http://www.saveonties.com/index.html.
http://www.absoluteties.com/index.html.

Definitely eBay!

try claire

Try Marks and Spencer. They used to do them.

If you go into any decent charity shop you should find one, afraid that modern fashions only do big bulky ones.

try ebay or resale shops

Try Envy they sell some but not many but they are sold at affordable prices and come in a nice range of colors too

ebay

try monsoon

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