Welcome to the club.
FWIW I have had no problems with Stens products other than wrongly marked belts which were replaced .
I have seen the rep once in 6 years, as he said, I am a small customer with not retail presence so I get treated accordingly, which is fine with me .
I don't know if they do it there because our markets would be very different but down here they do monthly specials which are really cheap.
Originally I ignored them unless it was something like oil which I use a lot of.
This year they were selling the 4 litre SAE 30 mower oil cheaper than I can buy it bulk in 44 gallon drums so I bought 20 boxes ( 80 packs ) took some photos of the mower oil in the big box stores , printed them out then went to a couple of car boot sales and shifted the lot .
The person I bought the repair run from does a similar thing but he puts them on ebay at a slightly higher price than the normal wholesale and is doing very well , but he did say you have to be quick to list them the same day that Stens sends out the specials listing.
Down here they give discounts on top of the computer listed price he is on - 20% I am on -5% .
They also give free delivery on orders over $ 150 so I tend to hold on to Stens orders till they get above the free delivery threshold so most will be stock replacement rather than single job orders.
If they do a paper catalogue, get one then go through it when you have nothing better to do . This will get your head around what they have & what they don't and the key words they use to describe things.
When I do an idler pulley , unless it is one I commonly fit or for a model I have an IPL for I just measure it then go to the idlers by size section & find one that is near enough, saves a lot of time .
Individual price differences are not all that great on a lot of parts but when you add up a big job it does make a difference x 100 jobs or more a season that can be the difference between a health profit & just getting by .
Also remember that they can pull your account as well and for the first year HO will be watching your orders to decide if they are making money on your account or loosing it , so if I was you I would be ordering everything from them if they stock it & the price was not dearer.
Order things like spark plugs in full box qualtities ( 10 for NGK 4 for Champions ) . You will use them eventually and it is more profitable for them to pick a 10 pack than a single plug.
Also buy in trade packs where possible . The 12 packs of oil filters are very cheap on a per filter basis particularly if you charge out at full retail ( I charge out at $ 2 off ) .
Same goes for air filters . You will use a full 25 pack of Briggs panel filters in no time flat particularly as the same filter fits a lot of Hondas as well , ditto for the prefilter & fuel filters .
So at this stage you can toss a few packs into each order to get free delivery & bulk out the orders .
If you don't have one, haunt the trash & treasure, car boot & similar sales and see if you can pick up a spark plug merchandizer or two .
They look professional & put tags on mine with the applications & gaps which saves a lot of time and by the time you hae filled it with the plugs that you actually use you will have spent better than $ 400 with them so you account will look good . I have an old NGK & Bosh + a Champion which I bought on special from Stens, I regret the latter a bit because while the plugs ended up being $ 1.50 ( Aus ) each a lot of them was what was common useage 10 years ago so are a bit slow moving , but it looks good in the workshop, they sit on the end of the parts racks & hide the junk behind them.