as for spices and flavours, dry powders such as pepper and salt need to be kept dry so any small airtight container will do a popular choice is the 35mm film canister.
other options are ziplok bags, silver foil folded, and you can collect tiny bottles from hotels wash them well and re use as condiment containers.
if you go into your local camping shop they probably have some sort of salt or pepper container, i guess just remember how much you actually use!
as for sauces again airtight containers but make sure it is sealed well! "Coghlans" make "squeeze tubes" which are excellent for anything from butter to jam and syrups i have used them to carry mango chutney for an indian i made once.
it's sometimes worth buying a ration pack they sometimes have usefull bits,
i bought a US army MRE ration that had a tiny bottle of tabasco in about 1" tall!
other things, when you go for a coffee or burger, pick up some free sugar, salt, pepper, face wipes even packets of sauce, vinegar ect.
they are there for you to take, and quite usefull to make up cheep camping menu's.
during my mountain leadership training i knew i would be away from freash food for a while, if you are away for a week or more it's worth taking some vitamin supliments too, just the one a day cover everything pill does the job.
an area which is always missed is washing up!
you can use the same containers 35mm to carry a small amount of washing up liquid!
make sure you use the concentrated Bio-degradable soap which can also be used for personal hygine and clothes washing, a very useful addition!
hope thats given you some ideas.