it depends on which overdrive specifically and what your budget is like...
let's examine some facts:
1. pretty much every overdrive circuit in existence today - except for a few notable anomalies - is based on the ibanez tube screamer circuit. "boutique" overdrives, again with a few notable exceptions, are also mostly based around this circuit, if not blatant ripoffs thereof. so ignore all the marketing blurbwords like "ultra-dynamic" "touch-sensitive" "transparency like never before" etc. and do a blind test instead.
2. this is NOT to say that all boutique overdrives categorically suck. there are indeed some good ones out there - and what do you know, also some that have a relatively tolerable VFM ratio (the xotic boosters). what i mean is - you might just be surprised with how much mileage you get from a $40 boss or ibanez pedal.
3. this is important - the tube screamer was not named so because it sounded like a tube amp, but due to how it worked in conjunction with a tube amp, slamming the input of the first stage. essentially, what i'm saying is, using a tube screamer with a run-of-the-mill solid state amp will NOT make you sound like zakk wylde. i've played my TS10 with a few different amps, and the worst results were with a fender solid state frontman - scratchy, fuzzy overdrive. nothing liquid about it. another interesting overdrive is the red llama, based on craig anderton's tube sound fuzz circuit. i built one of them and LOVED it with one of my amps, and hated it with the other. it sounded great on one solid state amp too. that isn't a proper overdrive per se, but somewhere between overdrive, sustainer and fuzz.
anyway, before i digress too much, i think it would not be prudent for you to spend too much money on what is essentially a line booster circuit with a bit of gain thrown in. i give you the following potential low-mid budget candidates, all of which are tried and tested and have a pretty big customer base, before you throw $400 on a pedal made by some clever marketer which contains pretty much exactly the same circuit:
1. ibanez TS9 or TS9DX (EDIT: oops, expensive. 8 and 9.5k)
2. boss SD-1 (NOT the DS-1) - i don't see it on bajaao, but musiciansfriend.com sells it for $39 new. so if you know someone coming down...
3. digitech bad monkey (cheep! cheerful! good reviews!)
4. mxr microamp
5. electro harmonix LPB-1 (not sure where you get it, i believe bhargava's is the EHX importer though. check with bhargavas bandra. also $39 on the fiend.)
i also hand-build pedals in my free time, but i'm really super-swamped with work right now and am not taking any orders, at least not at this moment. here's my work, if you want to take a gander: http://s812.photobucket.com/albums/z...tompbox%20DIY/ and you can PM me so i can earmark you for future projects, although i can't promise anything at the moment.
anyway, i think that any of those pedals should serve your needs well. do some research on their reviews, prices, availability etc. the microamp and LPB-1 circuits are more boost-like, the others have some soft distortion on tap too.
last word: gain is a tricky thing, and needs to be experimented with to understand properly. the rewards are immense though, be it for you as a player who uses different pedals to nail his signature tone or for me as an amp builder who "finds" that perfect drive by cascading differently voiced gain stages. good luck!