It can be difficult, but everyone has to start somewhere.
Not everyone is extrovert, many webmasters are often quite solitary by nature-shy even.
Many don't want/like the idea of their 'name in lights all across the net either' and prefer to stay under the radar. Doesn't make their products any less worthy or of less value because of their connections.

Remember the guys who developed Trivial Persuits (the board game). They went to every bank and joint venture broker they could find and everyone knocked them back. In the end they mortgaged their houses/sold their cars and well- eventually laughed all the way to the bank- so don't get discouraged. Keep building your lists and make friends with good people- who you may want to JV with later on.

If you have a good product, try approaching a few people, what's the worst they can do? Just be polite and respectful- they can allways ignore you if they aren't interested. I certainly don't turn a JV away just because I don't know the person who produced a product yet.
I'm sure a lot do- but we are all differen't.
You only need a few good JV Partners to get you going and you can keep your pool of JV's small too if that suits you better. Although some marketing super stars, of course have bigger lists- it can pay off to chance a JV with a less well known person - they may well do more promotion and put more effort in producing great results for both of you.

Sometimes it can be a case of quality not quantity- so don't sweat the numbers. Keep going
Thats my view- may not be everyone's....