Different pricing scheme, at least in the beginning. While $39 (or even $59) is acceptable as one time payment, I am not sure if I am willing to pay this for a product that's been on the market for only 3 weeks and whose future is unknown. Charging something like $1-$2 per month will earn you more in the long term and will provide a safer option for the customers (they won't loose too much if you disappear in a couple of months).
BTW, at the organization where I work, we can only make payments to established entities, i.e. someone who has address, account number and can issue an invoice. I guess Gumroad, as a middle party, can provide all of these, still it would add to your credibility if you had an "About" page with the necessary data. Oh and a Privacy Policy would be nice too - some organizations won't allow installing any extensions that are not reviewed by a security team and such reviews often involve checking privacy policies.