Rotten in order for others to give you additional advice on yeast please let us know what temp control you have, if any and what are your average temps for your part of SA. You've given us a snippet when you stated that you used lager yeast when things got too cold. Pilsener is made with a lager yeast so it may be too late for that at the moment. English ales as the name suggests tend to use an ale yeast which can be fermented at the higher temps, generally 16 degrees plus. I'm currently drinking one of Dr. Smurto's Timothy Taylor's Landlord.
I've recently made a few Kolsch style beers and have been very impressed with this yeast on the whole (low flocculation but I have a filter). Kolsch yeast ferments very clean like a lager but at warmer temps. Such yeast can often be used to make a pseudo lager. Having said that a psuedo lager can be made with US 05 if you can hold it at around 16C and make sure that it doesn't go to sleep. Wyeast 2112 - California Lager is also another psuedo style larger and is similar to US-05.
To save money on $11.50 liquid yeast then you don't need to do anything different to get better bang for your buck. You stated that you already reuse yeast and make starters(later you may go to cultures and slants, I'm yet to do so, and it's not worthwhile for me yet.
My recent brews have been Landlord yeast split into two, one refigerated and the other into the allgrain Landlord. I top cropped some of this yeast and it is in a grolsch bottle in the fridge too. Once kegged I put another AG Landlord onto that yeastcake which is has about a week to go. Today I bought a can of the new Cooper's International English Bitter and I'm going to put it onto the yeast cake for its third use if it all smells fine, if not I'll make a starter from one of the two bottles in the fridge.
In my second fermentor(60L) I have two cans of Coopers International Traditional Europeon Lager going with Kolsch II yeast. I've reverted to a few kits because of time constraints and the fact that the kits give me a better yardstick with which to compare the yeasts. My experimentation began after putting a Cooper's Pale Ale can onto Kolsch yeast from an all grain batch, The kit with this yeast was better than my all grain Kolsch, but both were very nice. When visiting tonight I was given a corona, the first I've had in a while. It's not normally my thing, but I've a mate that brews Coopers Mexican Cerveza so I've decided I'm gonna buy a can to through onto the Kolsch II yeast cake when it's done with the Europeon lager. Iwill also top crop some of the Kolsch II yeast this weekend.
I've written more than enough, you work out the maths from the $11.50 for each smack pack.
Cheers
Hirns