I don't really see you making 550 rwhp on your budget, but I could be wrong. T67 might get you there.
I recommend Driftmotion for the turbo kit, especially now since there's virtually no fabrication required for the 7M.
I have the T04 60-1 kit, primarily because I wanted to make good power without the lag associated with a T67 (or larger) turbo.
Their kit, all said and done with S&H will run close to $2K (maybe a bit less). Add an AEM UEGO for $300 (some might be less) and a EBC for $250 and you're at $2550. Big injectors will cost you another $250, bringing the total near $2800. This leaves you enough money to buy the Lexus AFM and a SAFC Neo, or you can just go with the MAFT Pro and do a speed density setup.
Right now I am using the SAFC Neo for fuel management and it works, but lacks some of the features needed for high-HP applications (timing control, etc.) I can tell you that the MAFT Pro is very attractive due to pricing AND a long list of impressive features.
Add this into the mix and you come out right at your $3500 target, with the SAFC being a little cheaper. This doesn't take into consideration the need for a bigger FMIC, or the larger diameter IC piping that you'll most likely want to run. Nor does it account for braided wastegate control lines and -AN fittings, or the sensors needed for the speed density setup.
Lastly, you WILL need a clutch. For 500 rwhp, you'll need a better pressure plate. It is possible that you can find someone to build this setup for less than $500.
All of this amounts to something in the $3750~$4K range.
IMO, a properly built 7M-GTE motor is just as good as a 1J or 2J motor any day, at least for the horsepower levels that most of us are trying to achieve.