I don't have exact figures, but I believe our costs to print worship aids in house is about half of what a subscription service would be. That is strictly on the basis of materials and per-print fees. That doesn't include my labor designing them, of course. We use 11x17 trifolds.

Things were even better at my last gig where we owned the printer and only had to pay for paper and toner, but there wasn't a print-rental fee. The investment in the printer paid for itself in a year.

Ultimately, no one can really give you a good answer for your situation without knowing how many worship aids you'd need to print per weekend, what style you'd be printing (to gauge how much paper you'd be using as well as per-print cost totals) and how much you're currently paying for a missalette.

There is also the question of licensing; if you already have one-license, it would be a wash, but if you'd be adding that in, that's something else to consider. We *have* to have OL here (cathedral, so there is always some something that needs licensing) but at my last parish, I did things that were exclusively in the public domain or creative commons and it was totally doable. I'd still say that 97% of what we do here is PD stuff, or things I've arranged myself.

TCJ, does that include labor costs (worship aid design and print job monitoring)?

In answer to the above questions...

Labor costs: No factor. I did everything myself, design, printing, folding, stapling. Yes, it takes awhile, but you can save them for using later if you stick with the same music every three years. Folding is a breeze when you have three kids to help.

Multiple Masses: We only used them for English Masses and not Spanish ones (aside from a few feasts), mostly due to copyright issues, but the cost comparison didn't include purchasing Spanish missals either. For the other English Masses, the music stays the same most of the time, so that saves costs. If there are any changes, they are minor and can be labeled which Mass. If you have to make separate for each Mass, then I'd think your savings might be negligible.

We have a paper folder, and any time we do booklets, our machine folds and staples them automagically, so that helps. All of my time investment is in the planning and designing.

If I remember correctly, we were also in the 5k/year range for about 300 missalttes at my last parish. OL+2k printing/paper also puts us close to 3k/year.

A good Martin Yale paper folder runs about 1200 (if you get the big one that does 11x17, but it pays for itself in a year from all the time saved. 400 worship aids can be folded in under 5 mins.

Kudos on doing your homework before presenting to your pastor.
I think your situation warrants worship aids even if it is not the most cost effective option.