Ok then, you’re limited by price as to what you can buy. So, you need to get the most for your money. You can always upgrade later if you're happy with the basic guitar and how it feels/plays.
I'd be inclined to get the Grizzly Heirloom Strat kit, except that it comes with an alder body with a curly maple veneer top, and you want ash. The pickups are better (Alnico), and I suspect that the tuners are better as well. As to the tremolo, I'd probably want to call both companies and as some questions, like, string spread width, mounting screw pattern size (like the Asian imports/Mexican/Squire, or std. American size).
The assembled pickguard that GFS offers is a pretty good deal, but you could upgrade either pickguard from the kit with alnico pickups, ALPHA 250k pots, a CRL 5-way switch, a Switchcraft input jack, cloth covered vintage hook up wire, and some better caps, all for under $95.00 USD (about $100.00 USD with CTS pots). Of course, if you were to do this, you'd have to install/wire/solder all the components yourself (but that's half the fun!).
If the body is drilled for a std. American mounting screw spread, GFS has a great Wilkinson vintage style replacement tremolo with a steel block as seen here on my blue ash Strat (about $42.95 USD):
So, get what you can afford now, and I'm sure that I speak for most here when I say that we'll be more than happy to help you through the mods at a later date as you can afford them. We're always delighted to welcome others to share in our affliction...
To shamelessly borrow from Shakespeare (with a slight "modification")...
Modding is "A madness most discreet."