Never been to Transworld but I think their website has costs up on it. The only convention I've been to is Midwest Haunters Convention and I keep costs down by not needing a hotel since I am within driving distance and only do the masquerade ball and one full day (as much as I would love to go for the whole weekend it's nearly impossible for me to get the whole weekend off work).
TransWorld is really a trade show and not a convention, although it is becoming, slowly, more home haunter friendly.
Factor in these costs:
Admission - $50 per person
Hotel - ~$150 per night with taxes included
Parking - $12 to $20 per night
Education - varies greatly...figure about $50 per hour of education
Events - depends on the events you want to attend...can range from about $45 per person for the City Museum party to more than $200 for some of the pre-show tours.
Then factor in travel, meals, whatever you buy at the trade show (and it is primarily a trade show for purchasing items).
Midwest Haunter's Convention is more of a convention. They do have a fairly comprehensive list of prices for attendance, seminars, and events on their website.
One tip for MHC (I've been there exactly once, so YMMV): Unless you REALLY want to go to the dance floor for the masquerade ball...don't buy the outrageously priced masquerade ball ticket...the real party is on the outside patio at the convention center's rear entrance. (Of course, now I'll probably be disallowed from attending for telling everyone that )
If you make purchases from Fright Props, when Transworld rolls around they will send you a letter which meets your requirement for registration. You have to contact them to get the letter, it isn't automatic. (check out the transworld website the requirements are there)
Abunai's figures are right on. Most of my cost, minus the necessities, was in the seminars and one haunt tour. I know now that I will take fewer classes next time, over extended myself a bit.
Also, Abunai, you'll be missed at MHC next year
The Transworld show itself isn't expensive. $50 for four days of show is cheap. Plus, there are several different events every year, some of which are free. The show, as mentioned before, is a trade show and is more business oriented. Not to say we don't have a great time.
I have been going since I was 19 and I enjoy myself immensely every year. I highly recommend!