The other lower end brand for Red Wings shoes is Worx, I think. It is much cheaper than Red Wings and if you are using them for working, it is better to get them. Red Wing shoes are too expensive to wear to work lah. ;p
A decent pair of Worx shoes cost around S$100. It also looks good enough to wear other than working times (when you go shopping, clubbing). In my opinion, it looks much better than the safety shoes most contractors wear on construction sites.
Do pay REd Wings at Far East Plaza a visit and look for Eddie or Bryan. They are very nice people and I am sure that they will advise you on the safety shoes you need for your activities.
There's the workman's standard issue King's Safety Shoe, which are very utilitarian in design. King's also has an alternate lineup of slightly more casual steel toed shoes called Otter. They come in low and high cut versions and a pretty waterproof. Below $100.
There's a hardware store near Sungei Road's flea market that deals in these shoes, they're in a HDB block facing the flea market.
SAF boots don't qualify as safety boots have a piece of metal above the toes to protect the toes. I'm not sure but there is a piece of metal in the sole. I am basing this on the King's safety boots that I have which is issued to technicians in SAF.
The SAF Goretex boots are made of crap quality. If you're lucky, they'd last you a year.
If you have to, get the older leather boots (only issued for certain boot sizes). Those last a lot longer but take some time to season. Very important for certain vocations like mine. Where going into the water and trekking though muddy areas is part and parcel of the job-scope.