Got your DSLR at last? I would strongly recommend a dry cabinet as well. Bite the bullet and save a hundred bux for it. In the meantime use tupperware with silica gel. But get the dry cabinet once u can.
YES! Silica Gel won't last very long if you open and close the airtight box every now and then. After that you will need to heat up the gel to dry it (not very healthy). Secondly, silica-gel can be quite dusty after a while... which is not very good for the DSLR image sensor.
Since you have already spent some money on a decent camera, paying another 10-20% more for a dry cabinet would be like buying insurance. Especially in SG's environment, it is a must. My advice is to get one with enough room in case you want to upgrade. You definitly don't want to stuck with one which you can only fit your existing gear and when you buy more gear, you will need to buy another.
In the past I tried to save by using air tight box with silica gel. I thought I can save some money. Guess what? my equipment turned mouldy and the service cost more than the price of the dry cab. Now I have learned my lesson. Listen to all the comments posted here. Go and get one. Don't be penny wise pound foolish and more to lose down the road.
A dry cabinet can last you for years (mine did!)...... while offering you peace of mind in terms of protecting your camera gears from the harsh elements (essentially humidity & dust). Work your sums and you'll realise it cost you only peanuts per day!
The cost of the dry cabinet is a pittance compared with the cost of your gear. Saving the 100-300 is really not worth the hassle of mould and repair. On occasion mould and fungus also leaves permanent marks on glass elements even after being cleaned. Get the dry cabinet, it's dumb not to.
How much have you spent on your gear now?
Should spend another 10% of that on Dry Cabinet.
Will you buy new camera and lenses for the next five years? almost certainly.
But you will not need to buy another dry cabinet for the next 10 years.
If you sent 2 or 3 lenses for cleaning, it will cost you a new 60L dry cabinet, why don't buy now?
Forget about using or recycling silica gel, it is a waste of time, in long run, dry cabinet save you lots of headache.