Opinions on some upgrades for my equipment

So I've been thinking about upgrading some of my equipment once I get my taxes back, I've either been thinking about getting a Aaron Cain coil machine or a good rotary,I've never used a rotary before but I've seen a lot of nice work done with them,any opinions? Also I was wanting to get a thermal printer,does anyone know a good one for about $300, I'm running kylin coil machines now,I've only been tattooing for 3 months but I can tell my work is getting better from what it use to be,I appreciate any opinions.https://servimg.com/view/19590405/7 this is the last piece I did it's not finished yet

And please critique my work,this was my first piece on dark skin tone but I was happy enough with it,I only charted him $30 since I only charge for my supplies and not the tattoo,thanks

Was it lined in purple??.. I can tell that quite a lot of lines are weak and probably won't hold,,

Save your money and learn to tune the machines you've got,,,

I appreciate the critique,I was worried about going too dark cause I heard darker skin can be more sensitive, but he's coming back in 2 weeks so I can touch up whatever I have too, I've spent a lot of my time tuning and tearing down my machines and I've got them tuned pretty good right now, I was just wanting to try something different and I heard the aaron Cain are flawless and cheyenn hawks are good,but I'll probably wait and just get a thermal printer,any recommendations on those? I don't wanna spend a lot of $ but I want something that'll last,thank you

okay, a couple of things I see going on right here. (for the next time I would suggest to post the picture in the tattoo section of this forum) you are quite correct about darker skin being more sensitive, but that does not mean that you can go to dark that it will hurt the client. (which makes me wonder, do you mean like going over the line over and over to get it darker?)
I have tattooed darker skin and one thing that I have noticed my self is that their skin seems to accept the ink quite well. what you do have to be careful is to not over work the skin since most of them are prone to scaring.
I agree with Dmerit here. I think that you have an issue with tuning by the way I see these lines. hand speed and machine speed might be an issue here as well.
I think that you might have an issue trying to go over the lines again when he comes back, I don't think even half of those lines are going to hold. and trying to set a stencil over it again to match what might still be there will prove to be quite a challenge in its self. I hate to say this but I think that you may want to try and tattoo something like a banana. trust me I know it sounds stupid, but when you are tattooing a banana you will see that the peel is really delicate. if you can lay a clean line on it with out cutting the peel with the needle, then you will be ready for actual skin. It will help you figure out what your hand speed and machine speed works best for you.

I appreciate the comments, one of my biggest problems with this tattoo is I shouldn't have changed the way I normally tattoo, I was so afraid of messing him up because he was my first dark skin tone tattoo that if what you say is right and I think it is that I'm gonna mess him up if I try to go over the lines again, lining and depth were one of my hardest things to learn and I'm still learning but I can usually line single pass lines, I haven't been doing it long but I can do it, my biggest fear is doing a bad tattoo so I might just switch back to the bananas for a bit, I'll upload a better pic when he comes back, I'm really trying to better myself anyway I can,I've taken my blood borne pathogens,cpr, and first aid classes for my safety and there's, anyway can yall recommend a thermal printer that's decent quality for about $300, I'm a single dad and usually don't have $ to blow on equipment unless I win the lottery or get my taxes lol

Personally I tattoo as normal on dark skin but I do notice it swells more and the darker the skin the harder it is to see what you are doing.