I work constantly with Ampicillin, Tetracycline and Kanamycin. If you're in microbiology I bet you do it to. Tetracycline and Ampicillin have already been reviewed here. So why not a quick review on the most interesting facts concerning this aminoglycosyde.
Brief Description: Kanamycin sulfate is an antibiotic effective against both Gram-negative and Gram-positive bacteria, and also effective against mycoplasma (a genus of bacteria lacking cell wall). The way it performs its action is by attaching to the 70S ribosomal subunit for inhibiting translocation (a transfer of a chromosomalsegment to a new position), thus resulting in miscoding. 
Molecular Formula - C18H36N4O11 
Therapeutic aim: Antibacterial aminoglycoside 
Molecular weight: 484.49864 
Obtained from: Streptomyces kanamyceticus from Japanese soils. 
Biomedical effects and Toxicity: excreted primarily by the kidney, through glomerular filtration (mostly), but also in a lower percentage by the tubules;
- merely a maximum of 1.5% of ingested Kanamycin is excreted in the urine due to poor enteric absoprtion, i.e., bad intestinal intake;
- mostly eliminated in feces since the gastrointestinal tract doesn't really absorb this complex chemical (~1% of an oral dose is absorbed by the gastrointestinal tract);
- in 24 hours 80-90% is excreted by the human body after glomerular filtration. 
Decomposition: heated to the point of decomposition produces toxic fumes of nitroxides .
Form: Usually white powder crystals dissolved in methanol and ethanol .
Price and Availability: I found on a randomly selected website the following prices - 1g costs £30.70 as 25g can be purchased by £342.00, cheap hum?!  I guess it is, considering that a stock solution of 50mg/ml of Kanamycin monosulphate can be used for long if you freeze it. Work concentrations for Escherichia coli are 25µg /ml and for Pseudomonas aeruginosa quite stronger, 300µg /ml.
Protocol for preparing 10ml of 50mg/ml Kanamycin:
a) Dissolve 500mg Kanamycin monosulphate powder in 10ml distilled water;
b) Filter-sterilise the antibiotic solution using a 0.2µm syringe filter (see last image);
c) Aliquot volumes of 0.5 to 1ml for avoiding constant thawing and freezing;
d) Store at -20 degrees Celsius.
 Kanamycin, Drugs.com, [http://www.drugs.com/international/kanamycin.html], last visited on the 19th of June 2013, last update on the 17th of May, 2013
 Kanamycin, PubChem, [http://pubchem.ncbi.nlm.nih.gov/summary/summary.cgi?cid=6032#itabs-2d], last visited on the 19th of June 2013, last updated unknown.
 Kanamycin monosulfate, MPBio, [http://www.mpbio.com/product.php?pid=02194531], last visited on the 19th of June 2013, last update unknown.
 Kanamycin stock, Wikiformulation, [https://www.wikiformulation.org/protocols/50-mgml-kanamycin-stock/10093], last visted on the 19th of June 2013, last updated on the 18th of June 2011.
 0.2m syringe filters, Tissue culture and laboratory technology, [http://tpp-usa.com/docs/TPP_02um_Syringe_Filters.html], last visited on the 19th of June 2013, last update unknown.