Anyone have a rough estimate for an upgrade cost from Main to Comfort+ on a JFK-BDA flight? And if you are Comfort+, where does that put you as far as boarding order? Do they have additional options to bump up your boarding order for a fee?

I travel to Bermuda for work all the time, usually on American, and this is the first time a Delta option is coming up to book. I'm trying to decide if I want to go with the usual or give Delta a shot. I usually book the cheapest flight through work and personally pay for an upgrade to the extra legroom seats. It usually costs me around $70 RT to upgrade on American (plus an extra $35 if i want even better boarding). I've never really flown on Delta and not sure what to expect. I don't want to book it and find out its super expensive to upgrade.