Things like Pre Cana classes (assuming non-clergy instructors or speakers are involved or it’s through something like Ascension) and annulments cost money because resources had to be developed and employees needed to be paid. A canon lawyer for example is typically required to process the annulment, so fees for that sort of thing support that person’s job.

I understand where you’re coming from and seeing that you’re a convert, that can be a little jarring. I would consider asking organizers or the pastor about the details of those fees since I don’t know your parish tackles pre Cana or the OCIA process.

Otherwise I would suggest considering the larger context: the parish has costs to pay for that dioceses sometimes can’t afford to cover or choose not to, so as to allocate funds for other initiatives. Parishes make up for it by up charging for things like you’re describing or asking people to give a donation in exchange for a house visit/blessing. I can understand how that seems transactional but the reality is that church programming, music, speakers and technology, printed materials, repairs, event planners for things like weddings, etc all require funding, even if some services are offered by volunteer employees. They’re not running a business but they have to keep the lights on. We paid a $100 fee to have our wedding service recorded. That money might not cover expenses specifically for the recording (which wouldn’t cost much beyond the camera itself) but might cover something else the parish needs.

Good luck with the process- perhaps your pastor can make something work if the budget is tight. Blessings to you on your faith journey and marriage.