How expensive is it to go on a retreat to a convent? Is there a large difference between a group discernment retreat, or going as an individual?

It doesn't cost too much...for an individual visit, they may not ask anything from you (but you can always give donations.) From what i've experienced and seen, for a group retreat they might ask for a donation of around $20-25 dollars.

Yep! Usually the case!

it depends too how far you are traveling and so on.

For my order, vocations visits are no cost. The costly thing is usually the transportation. Gas costs so much, and plane tickets are usually about 200 (I've paid $140 for my cheapest and $214 for my most expensive)

I was just telling someone this in another thread...
Visits to Our Lady of the Angels Monastery for discernment are free. They aren't retreats, but you stay in the guest house for a few days, which provides everything a regular house has, and the sisters feed you, and the brothers give you transportation to and from the guesthouse. The housekeeper of the guesthouse is paid by the Shrine, so you can make a donation but it's not required. The only cost is your plane ticket.

And even if there was a cost and you were having some financial problems, I'm sure the community would be more than happy to help you out!

Yeah that is probably true.

I've visited 5 communities so far and I haven't had to pay for anything beyond transportation.. For one community, they reimbursed me for my train ticket because they have a nice benefactor for that.

About visiting by yourself or with a group, I think they're are pros and cons to both. I've only gone by myself or one other person but I like it because you get the Sisters all to yourself! selfish I know.... but with a group you get to meet other discerners and they usually have more planned activities and group bonding stuff.

I'd like to have one other person there....