how to reach my TARGET market

[tomicash.com]

let me begin by saying i had NO idea how hard it would be to market a FREE site...that being said, does anyone have any suggestions for reaching the following HIGHLY SPECIFIC markets?

1. People who travel frequently on business, but would love to save an extra $40-$50 per hotel stay.
An excellent example would be a friend of mine who travels frequently on business. His company lets HIM book the hotel and then reimburses him later on (that is, they do NOT book through an agent). This way, I can get him a $50 rebate that is completely separate from the bill that his company reimburses him for (earning him $50).

2. People who sell high volume repeat items on eBay and want to save on their eBay fees. I know I can just start randomly emailing eBay sellers, but I don't want to spam (gives a bad image).

I have other niche markets I want to target, but these are my major focus right now.
Any info you can offer on the MOST (COST) EFFECTIVE way of getting through to this market, online or OFFLINE, would be appreciated.
thnx

[webchalkboard]

Maybe you could think up a novel Facebook app and try and spread it virally.

[steb]

PPC ads would probably target the hotel room buyers well.

for ebay sellers, im not sure - are there any community sites around? you could advertise on them either directly or through adsense if possible. cold contacting sellers may be the most direct way. If its personalised, you wouldnt really be spamming in a "bad" way.

[webchalkboard]

Yeah I never know if it's ok to cold contact people in a personal way or if i'll be considered a spammer. I'm always creating sites, like my latest one webchalkboard.com for example. It's a really cool site (I think anyway) and it's certainly taken me ages to develop. The hard bit is getting the word out there, and I think that requires something I don't have a lot of spare and that's money! Lol.