I also have BPD, and I definitely internalize a lot. If you ever want someone to talk to about it, you can always send me a message! ♥
As for your questions, I am lucky enough to have insurance, because therapy can be very expensive. In fact, I still can't afford to go to the group therapy I'm supposed to every week. But depending on where you live, there are low cost options. I live in a very rural area, so there isn't much around here, but you should be able to look up what is available in your area online.
Before I began therapy, however, I used a ***** Group that posted actual DBT lessons and activities each week. It is called "dbtclass" and is on *****; I'm not sure if I can post the link here. This was very useful to me, and now that I am actually in DBT, I know that the lessons I received in the online group are actually taken from what you'd learn with a therapist. I would also suggest reading some books about the disorder, but with BPD especially, you have to be very careful that the books are respectful and accurate. I have read some that had me in tears, believing I was some kind of monster for having my illness, because they were so inaccurate and cruel and just not good.
Another sad thing about the disorder is that medication doesn't really treat it. Medication can help with the anxiety/depression, but as for BPD itself, there is no pharmaceutical cure. But I promise you that you are not hopeless and if you have any more questions and concerns, feel free to ask! Good luck with everything. I'm so sorry that you're going through this, relationships and employment and pretty much everything while borderline is a huge task, but the fact that you're still around proves your strength.