Many schools have funds set aside so students can participate isn such experiences. Ask your PI how to go about applying for them. I would bet that she/he isn't going to pay their own way to get there.
Here is
LizzyM's ranked list of how various research experiences are viewed by adcomms:
11. Housekeeping and supply ordering.
10. Helping others with projects, serving as a research assistant or technician.
9. Animal surgery.
8. Pilot work prior to writing a proposal for a testable hypothesis.
7. Responsibility for testing a hypothesis.
6. Funding of your project (not your PI's funding)
5. Poster presentation at a student event
4. Podium presentation at a student event
3. Poster presentation at a regional or national meeting in your specialty (published abstract)
2. Podium presentation at a regional or national meeting in your specialty (published abstract)
1. Authorship in a peer reviewed, national publication.