What should I merch in MapleSEA (Aquila)?

I only can provide basics for people earning mesos.
Make intermediate crystals then sell it for people who need to buy it.
Abuse events that give chaos scrolls / clean slates. Collect them as many as you can and sell the scrolling service. I did it when I was in Fornax, not sure with Aquila.
Collect event coins and sell the coins service (for example: buying frosty scrolls and upgrade the armor / weapon anid sell it as scrolling service / sell frosty ring)

Hope this helps. Although it's slow, but frosty ring is better for making some mesos for your situation.

PS: I played MSEA (literally quitted) and GMS.

I did do the intermediate crystals quite sometime ago and the events now, not sure if it is a possible abusable event. Cause the current event is the "Go Go Mesoranger" which provides you with equipment if you have met certain criteria. The other event is not worth mentioning because the equipments they give are u tradable unlike the mesoranger suits you get from the "Go Go Mesoranger" event. The mesoranger suit probably sell for about 10-15mil (not really sure) but the prices have been dropping. Well another thing you mention is the Frosty Ring and for MapleSEA the frosty rings are not really worth merching now because I seldom see people sell these and usually they would be priced below 150m because this event has started quite some time ago and most players have already obtain the ring. Lastly it's really hard to sell scrolling services because its reputation has been tarnished by scammers. Well that ends my point.

But thanks for your reply and opinion, really appreciate it.

For stuff like this, you should be posting at PPF, since most maplers here are in GMS.
Anyway, you provide us with no info. Are you funded or not? Are you a quick leveler or not? There are so many things that you can sell, for example, SBs, cubed equips, powerleveling service, and more.

Well I'm not really that funded and I don't think I'm categorised in the quick leveler type. The items I have are mostly SB's that I got from MMB's and also some percent stat Half Earrings (mostly between the range of 6% and 12%), I can't sell these items because I don't have the correct price and usually I will put some random figures to price these items, which no one will buy considering the how overpriced they are. So currently I'm finding someone who can give me P/C on items before I can merch them all and clear my inventory before moving on to the advance. I'm sure having P/C would help on merching a log but the thing is I can find away to get them. By the way may I know what is PPF?

Thanks for your comments