The traditional level 1 spell, Identify, has a major limitation not often actually imposed by DMs:
"The item to be identified must be examined by the magic-user within 1 hour per level of experience of the examiner after it has been discovered, or all readable impressions will have been blended into those of the characters who have possessed it since"
Essentially, unless you can cast Identify in the dungeon, or you can return to a town with a magic-user who knows this spell - and the means to pay him to use it - within a few hours, it is of no use. Without Identify, you are left with expensive enquiries to Sages or Bards, or simple trial and error.
This is such a huge mismatch between expectation and reality that I wonder if it is by design, and that Gygax expected player characters to research an improved version of this spell. (I actually did this research last year but forgot to blog it)
Macho Mandalf's Greater Identify (Divination)Level: 3 Components: V, S, M
Range: 0 Casting Time: 3 turns
Duration: 3 segments per level Saving Throw: Special
Area of Effect: Once Item
So, what did all this cost?
Dungeon Masters Guide Page 115, Spell Research Greater Identify
For this spell the Minas Mandalf University Library was used for reference, so that all may benefit.
Duration of research: 3 Week base (minimum 4)
Note that according to the DMG formula, adjusting the chance of success upwards is VERY expensive. A domain would need to be at least an order of magnitude more wealthy to consider such spending.
However, when you consider the conditions under which spell research is possible, the cost in time may well be a bigger loss; if you have the money then finishing the spell research ASAP could indeed be worth it.
Base cost 600gp per week.
Weekly variable of 300 to 1200gp for additional materials.
Duration of research: 3 Week base (with a minimum of 4)
After success on the seventh week, the total expenditure ended up at 8700gp. (we'll need to charge a lot of adventurers to recoup the research costs on this one)