If money is a problem i would stick with what you have because of a few reasons. Your channels isn't really the type of channel that will invite tech people or movie buffs or even animation guys and these guys pick up on every problem. Also keep in mind that any feedback really comes from you tubers with channels and not general surfers of your main subscriber base which in fact don't really care all that much about absolutely clear crystal sound if they did you tube would have been dead years ago, many channels have become massive with bad sound quality in the day of cracker jack mics from Christmas. Many watch channels on touchscreens which cant possibly output the quality some channels have and many watch on mobile while washing the dishes. To me your channel sound is fine for beginning a you tube channel, only a small amount of channels actually profit and make it a business out of millions or trillions that try, so being mindful of money is a massive realistic thing to keep in mind. As long as your sound is decent and clear enough and you have decent recording software then if money is a problem then i would use your cash to sell your brand and your self because the type of subscribers your channel will be pulling in, i would hazard i guess , wouldn't really care about top crystal clear sound quality. I have found that most people are aware that when a channel starts it starts with the basics and they upgrade as they grow, this can be good for subscribers as they then feel like you are rewarding them for their support and that they have grown with you.
I would image also that your channel will also be watched a lot by the younger generation or people sat up in bed and so on. Your sound is fine for a good while yet, don't rush out and spend your cash. My son has a gaming channel where he muffles into his mic, coughs and splutters everywhere and he just recently got over 15k in one week on one vid alone and his sound is awful, i know i bought him it lol. He wont advertise my channel on his, not good for his street cred he says hahaha.
good luck with your decision haha and channel
kind regards
Dadrules