[TriEmbed] Driving a bunch of solenoids (cheaply)

[The MacDougals]

I want to drive 16  solenoids
(http://www.sciplus.com/p/12-VDC-SOLENOID-VALVE_49518).  They are 12V, 100mA
devices.  At most 8 will be on at any time.  Assume 100% on time for any one
device.

I have been using this N mosfet for driving motors for my cat feeder and
drip irrigation: FQP30N06L

It works for driving the solenoids.  However, being a cheapskate, I am
wondering if there is something less expensive (FQP30N06L is $0.95 at
Sparkfun, more at Digikey)?

I will likely be using ATTiny84 to an I/O expander like:
http://ww1.microchip.com/downloads/en/DeviceDoc/21952b.pdf

I know I will need diodes across the solenoids to suppress the back EMF when
they turn off.
I was not planning on any opto-isolation.
I will probably be using a lead acid battery to power the solenoids.

Thanks.

---> Paul

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