Bitcoin is obviously an expensive investment, most especially if you are trying to accumulate the whole piece of it. But if you are trying to do dollar cost average regardless of the amount, you will not feel the expensive price anymore as you are only investing every now and then the amount that you can afford to lose.
However, the only thing that you should worry is that if you are not patient enough to hold for that long term. DCA will be useless if you suddenly resort into panic selling everytime the market is crashed due to market price correction.
In fact, the DCA model will indeed prevent you from panic selling, but additional capital is also very necessary, otherwise how can we consistently accumulate every drop of BTC if we don't have sufficient funds as you mentioned above.
Regarding profits in BTC, it will show itself because I am sure that everyone can record it, even if they only buy $20 using the DCA technique, regardless of the price increase or decrease.