Im no profession by any means but we all have to start somewhere. It's not a matter of buying lights but using what you have available. Try to shoot in a lighter room with more windows or even grab some lamps from around the house and bring them to where you wish to shoot.. Just don't mix and match your lights, try to keep them all the same tungsten, florescent and natural sunlight etc you want to keep it consistent. If you can come up with a few bucks try to find a cheap desk lamp or too with the adjustable arms. garage sales would be a good place to start. Desk lamps are pretty easy to position on the floor, on a book shelf etc. Pay attention to whatever program you are using to render your video and make sure the compression setting are set properly and you are using a good codec i personally use H264/MPEG-4. All your video seems to be done from a tripod so is doees not seem to be an issue. As stated up above the 50mm 1.8 is a great low light lens and you can probably find it used for $60-$80 on Craigslist or kijiji so keep that in mind for Christmas or birthday time. The only issue is shooting at 1.8 you will have a limited DOF. There are some great people in this forum better qualified to give advice then me but i think this might help you being on a budget. and when in doubt go watch some educational videos on youtube the resources are endless for learning.