Anna - you can re-use dry yeasts.
The stuff on the bottom of the fermenter is largely yeast, more so for kit brewers whereas AG brewers will have cold break proteins etc but i digress.
When you empty the fermenter (either to rack or bottle) you can re-use that yeast. 1 cup of slurry is approximately the right amount for the next batch. The whole yeastcake is way overpitching and whilst a lot of people do it and will tell you its fine, its overpitching.
So the next time you use US05 or S04 take a sanitised cup and scoop out some of the yeast and pitch that into your next batch. One re-use halves the cost of the yeast per batch. When i use liquid yeast i pay $12-13 a pack. I get at least 6 beers out of that.
As long as your HBS has a decent turnover of the yeast then you can be assured its in better condition and is a better product than kit yeast. Use the kit yeast as nutrient for the good stuff by boiling it for 5 mins.
On the topic of not sanitising bottles. With all due respect to those who say they don't, you should. Do you only sanitise the fermenter and not the lid or the o-ring. Of course not.
Anna - I would encourage you to ignore all the learned wisdom from those who have 'been doing it for x years and never had an infection'. To me its like eating your food off a clean plate but using dirty cutlery. It's a half arsed approach to sanitation (yes, I realise my example was for cleaning not sanitation but its a similar concept).
It's not that much effort to add some no-rinse sanitiser to each bottle, put a lid on and give it a shake. Leave for a minute or 2 and empty. Done. Sanitised.
No rinse sanitisers are cheaper to use in the long run and are much more convenient that those that require rinsing. I make up 10L of mine at a time and leave it sitting in a cube. It doesn't go off as it is acid based (orthophosphoric acid) and can be re-used. I bought 2.5L of 85% acid more than 2 years ago. I have used less than 500mL.
Not sanitising bottles and lids is lazy. I really don't care if it has worked for some people for 50 years. It's still lazy. Advising new brewers to do the same is reckless and it shits me. Keep your bad habits to yourselves please.
You can never be too anal about sanitation. Ever.
Rant over, caffeine slowing working its way into my system. I'll chill now
Cheers
DrSmurto
Anna
Anna
.
).
. Every so often to ensure that there are no problems with infections from the fermentor I use a strong sollution of Brigalow sterilizer, sodium metabisulphite and soak everything in that overnight and pull the tap out and soak it with valve open afterwards. It is nasty stuff and you may choose to use something different and that is fine. My point is to I use a different sterilizer to what you normally use in case some nasties have built up some form of resistance. Do this well beforehand to enable time to soak the fermentor overnight again with your standard unsented bleach solution and then still enable time for the fermentor to air dry. Rince very well with boiling water sever times before use. 
And this last point is one of the reasons I'm so interested cause I solved the(my) problem but I'm not 100% on how I did it!
