id also consider the yokomo sd sport. $150. shaft driver which is much better for street use or parking lot use with minimal maintenance.
I run a spec R s1 in my 17.5 class now too. picked it up to try and showcase a lower cost of entry into racing with our club. replaced my serpent s411 with top of the line electrics with this car and the cheapest roar approved electrics i could get my hands on.
im sitting at just over $300 for the car with turnigy batteries, savox servo, speed passion power and ive been able to keep pace with my serpent in 17.5 just fine.
the guy who beats me, beats me no matter what lol. i guess you could look at $500 cars from two stand points. if your fast, they can make you faster if setup to suit how you drive.
if your not fast, they can often be safer and have a wider window of setup. or hide poor setup better than cheap cars. my spec r was an absolute pig until i spent some time figuring it out.
I also really like dealing with tqrcracing for my parts. being in canada, i can whole heartedly recommend their service.
Sanwa M12 - Xray T4/16 - Xray Nt1/16 - CRC XTI-WC - ProAMPS - Hobbywing - ReVTECH - ORCA
www.irocc.ca - www.wcics.ca - www.vrcworld.com