ok this is what i have:
RHB5 turbo ($50 and i'd rebuild any used turbo...you forgot to mention the cost of running the water coolant lines as this turbo is water cooled that means t valves)...now did you get your turbo ported?
adapter plate ($40 from sites that sell them or custom fab for $20)
CX manifold ($20 local junkyard)...i'd definitely have it ported as a lot more air is going through this unit...in fact i'd get a ss header made to reduce weight and allow it to disperse heat better...read corky bell turbo book
V-AFC (!!!!a v-afc new is around $350 (version 2) and you can't find an used v-afc for less than $200!!!...this blows the $400 quote you have out of the water)
DSM 450cc injectors (used? new?...new they cost $50 each...why not get a set of mustang gt injectors as they will work and are much cheaper new)
custom chargepiping (this costs at least $250 for a high quality work and reliability)
boost gauge ($20 used)
a/f gauge (i'd go with a wideband as they are much more accurate than a cheapo a/f guage)
oil feed (ss flex line with AN fittings)
oil return (tap and mount return line into oil pan and AN fittings)
DSM smic ($30 i agree but good charge piping ups this price significantly)
probe/mx-6 bov ($10 used maybe...but you have to pay for a bung to be welded onto the charge line)
you mentioned turbo timer earlier thats $50
don't forget a fuel pressure guage
don't forget to consider an oil pressure guage (big deal in my book)
don't forget tuning the car on a dyno

now you spent all that money but: what are you going to do to cool the engine better and prevent heat soak???...oil cooler?, run front bumper venting?, vent the hood?, phenolic intake manifold & tb gasket?. etc.

you can say you spent $400 for the core turbo kit (no way a v-afc will fit this budget) but don't forget all the ancillary things you'll have to do...i've seen time and time again those that have tried to do a cheapo turbo spend around $700-$1000 after problems occur and drawbacks they did of a bargain basement turbo kit...you can do it but it's not reliable until done right