o hai guys: You seem like you are pretty squared away guy since you took the immense time and effort to create a good product.
Please don't take this the wrong way: Don't ever freaking take a shit, where you eat.
In other words - don't use your sisters girlfriends. You will ALWAYS be indebted to them, FOREVER (even if it's illogical since they only did one photo shoot for you). In their eyes you will OWE your success to them (which technically is bullshit but try convince them off that).
It's always better to pay for what you need and since there are a ton of different methods of marketing a great product - you said you are spending 40k-50k on marketing already - pay the extra couple hundred. To me the couple of bucks, are worth the peace of mind.
Hire yourself a professional photographer, advertise on craigslist and mention that you are looking to trade headshots for them appearing in your advertisements if you REALLY want to go down the hot chick route...
Go the Guerilla Marketing route for instance: Which site/blog/magazine would you like to be featured in? Now, go to Facebook and see if folks in that firm have accounts, that are linked to their company. Next create a facebook marketing campaign and target only their 50 employees with 2 different campaigns.
You can do the same thing for Good Morning America etc. etc.. Find out who their staffers are and do some innovative targeted marketing.
Where is the firm located? What other firms are located within a 2 mile radius? Is there a billboard for rent, which you can advertise on? Will cost you a couple grand but ya think they might react/get curious seeing a billboard that's located directly across the street?
Who are the most influential bloggers/writers that would cover your game? Get their email addresses at which point you make a game out of it - create a website like - Doyouwanttoplaythegame.com (didn't check if that site actually exists - you get the gist) then on the webpage all it says - Do you want to play the game? Underneath you put an easy riddle for them to solve sending them to an image, that gets their curiosity going like kickassscreenshot but make sure it ports them to a different website. Now, they are emotionally involved and want to see what else is there....? Make the riddles harder - the payoff could be a trailer to your game and a little submit form (For a free game including shipping fill out form). Now you have their name and address. Send some swag their way.
On another note... you could make this a fun game for the game community.. simple webpage with blinking cursor and the riddle... Trust me - real gamers (and those are the guys that'll spread the word for you) will eat out your hands doing this.
Another idea - find some of the biggest gaming websites and look at their forums... Who are the mods? Who are the most established members. Then contact them and ask them to beta-test for you - in exchange you'll plant little easter eggs into the game. Think about it: How cool would it be if you played Halo and somewhere randomly is an image that says in graffiti art - 'o hai guys was here'.
Long story short - do your research and then offer your target group, an unusual (outside of the box) hook that get's them interested.
However, pimping out your sister and her hot friends... wouldn't go there... Unless... hold on... how about some nekkid pictures of her here on WF???
Thought so... don't do it!
^^I agree 1000%
Bro don't ever use family members or friends. Also go on to GFY Webmaster Board and make a thread that you need shots with your game and check everyone's rates. You can get like 5 really hot girls with shots for like $500 easily. If you really want to hit it hard get a well known pornstar to do it (PM my friend has made sites for some so I can prob get you good deal
There are so many ways you can market this. Look at Evony and their hot chick campaign that shit blew up everywhere.
AIM me for more info i-a-m-d-o-t-h-a-c-k without the -