I owned a E92 335i with a manual before I made the move to an M3 so here goes...
Honestly, I think the only car that can touch this is the M3, for any other manufacturer to think for even a split second that they have something that can compete with the 335i is just plain dumb. Hell even the S4 which only got marginally better reviews is in the M3 price range. For the cost of the car, and the gas mileage itll give you, lower maintenance costs, and warranty coverage from various recalls, this thing is an all out steal. If you want M3 emotion it will take some extra cash but you can add that to the car as you go and free up funds.
1. Cobb Tune
2. Down Pipes
4. Light weight wheels
3. KW V2 or V3 coils
5. Exhaust (axel back for sound or down pipe back for power)
6. The sky's the limit
I had a Cobb set to stage 2 aggressive, downpipes, and an axel back and though I love the M3, I honestly miss the freight train like torque, my 335 was a true sleeper. Immediately after I traded it in for the M3 I had a few days of remorse where I thought I might have made a mistake, but thats where the M3's prowess comes into play...
If the funds are there the M3 is the clear choice because when you are driving an M3 you are driving something special, and what I honestly love about it is that its not obvious. Aside from a hood bulge and flared fenders, the car looks like a 3 series, the styling is just subtle enough to make anyone look at it twice and know its up to no good. Once i got comfortable with the car I started to realize what everyone is always talking about. Im pretty sure I will always own an M as long as it is possible for me to.
With all that being said, I your situation, grab the 335, save the money, itll be cheaper to buy, maintain, and fill with gas. I drove the car to have fun with it and still consistently got 20 mpg in the city/suburbs, highway was almost 30, its crazy to get that kind of milage out of a car that had roughly 390 hp and 420 lbs of torque after mods. You'll love the manual, please dont get an auto. The actual leather isnt as good as M, but great seats nonetheless, other tech like audio, etc. are pretty much the same. Hope this long as write up helps, good luck with the business... "the day is always dark before the dawn"