I saw that the bounty values are starting form 50rep. What if we can have values lesser than 50. It is not required to award a question with minimum 50rep. If there can be some more values to award as a bounty starting form 25 then it can be possible to drag more attention to a question asked by an user who has less reputations.
It is just right. To be considered a fully-fledged member of the site, gaining 50 rep is easy in a single day.
The bounty system is to get attention for questions that are difficult to answer, not an express support queue. A question can only receive a bounty after 2 days anyway, more than ample time to get 50 reputation.
I honestly think 90% of users that set bounties are misusing the system due to lack of understanding. You're paying for advertising your question, not express support.
Also, it's easy to get 25 reputation on a single answer. Just accept it and up-vote it, and you have given someone 25 reputation points. With that in mind, what would my motivation be to answer a question when I don't get any more for my effort then I can normally?
Lowering the minimum rep offered for bounty would only serve to water-down the featured question queue. If the question is genuinely in need of more attention (or is worthy of more attention) then it's worth 50 points (at least!). A 25 point minimum would simply encourage gaming the rep system (i.e. always promoting your own mediocre questions in hope of drawing a few votes) and would make it harder to find genuinely deserving posts.
Just earn a few more votes and offer a worthwhile bounty if the question deserves it.