Brief Answer:
Everything is cheaper. Literally. Everything.

Detailed Answer:
Opana is the newest, long acting, narcotic. Any generic will be an entire decimal place cheaper.
The general cost of opana per month is going to be at least 300 dollars. Since that is for about 10 mg a day and people might use a bit more, this could easily go to over 500 dollars a month.
Full price suboxone would be 600 dollars per month.
Contrarily about 100 of percocet 5 to 10 milligram would be in the range of 50 dollars (a decimal place cheaper).
60 tablets of 2 mg dilaudid is in the 20 dollar range.
http://www.goodrx.com/dilaudid

now, this is all quite a lot of narcotic and in a range that would be quite concerning for risks of dependence, tolerance, addiction, even overdose, but I am just answering a general question about pricing. These are national prices and while they will vary, they will likely vary more in the same town between pharmacies than they will in one state or one region than another.

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Brief Answer:
The long acting are also expensive

Detailed Answer:
except for some long acting morphine which is ruled out.

But all of the short acting ones are inexpensive. Hydrocodone (there's a new long acting version out--expensive), oxycodone (oxycontin, if it's generic it is cheap), hydromorphone (as mentioned), tylenol III but it is limited in how strong it is and it doesn't work on a lot of people at all, suboxone is a long acting but has limitations. Methadone is both long acting and very inexpensive.

There are limitations on methadone.

It used to be the most fatal narcotic (when it was at high doses), it is therefore limited to low doses that can be given in large handfulls (by pain clinics or end-of-life care) OR given by methadone clinics.

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