Credit card processing fees are pretty standard across every provider - 2.9% + 25-35 cents per transaction is about as good as you’re going to get unless you’re doing millions of dollars a month and can negotiate.
The only real options for keeping fees down are:
payment by check, which comes with the crappy side-effect of some % of your job becoming chasing and depositing and recording checks. You do not want to do this - trust me.
ACH payment processing, which I think Nexudus supports through a number of payment gateways. Stripe, for instance, charges a 0.8% fee and a max of $5 per transaction for ACH transfers.
BUT there are two big things to know about ACH: first, it requires that your members pay with a checking account, which many prefer not to, and also requires that they have their bank account/routing info collected as part of signup which is typically less convenient than a credit card. Second, ACH payments can take 7-10 days before they hit your bank account, which is MUCH slower than the typical 2 business day wait of credit card processors.
So, it’s possible! But comes with some non-trivial tradeoffs.
Credit card processing is a cost of doing business, and has significant upsides of speed, reliability, and ubiquity. I’d consider baking those costs into your membership fees rather than introducing friction to getting paid.