I know this is a relatively old thread but for those members that are looking to just replace the bulbs (vs LED mod), I managed to find the source for both the smaller bulbs and slightly larger bulbs behind the climate control.
Majority of the switch bulbs used for my 2004 MDX were the 14V 3mm Wire Leads T-1.
The larger bulbs used behind the climate control was 6mm.
Both was sourced from the seller DashBulb (Pioneer Radio Knob, Honda Accord Dash Bulbs items in DashBulb store on eBay!
I'm not him or associated with him in anyway other than he helped me out find the actual replacement bulb, even though the bulb was not listed. He had great communication and shipped the bulbs really fast (this is just the bulbs and you reuse the OEM plastic seats and the bulb cover, if any).
The cost would be at least 1/3 of going to the dealer, depending on how many bulbs you buy per order (I've ordered 20 for the 3mm bulbs in the past, 10 for the larger 6mm bulbs just recently).
You've also seen this posts that once you mess around, the other bulbs that was working will also go out as well so it is good idea to order more than you need today.
Also, 6mm bulb was right size from the width stand point, the bottom base came bit larger so it won't fit as flush as the OEM bulb. However, lead length was perfect and seems stable once lead was bent appropriately.
Thought I should post other options for those just looking for the OEM look and saving some few $.