Direct sales are the most profitable ad solution. Adsense only works (makes you more than a buck or two) with large libraries of content - popular content with high search numbers and lots of advertisers in that space. ie. Articles about dieting and debt will bring you more per click than technology.
The best way to make money on a small site is to go out and contact active advertisers (people advertising on sites like your own) and having a low (no-brainer) price for ads. $10-15/mo. for a small 125x125 px ad will bring you more than an adsense banner (for the majority of sites).
Affiliate marketing is also a great alternative. Find other products like your own and include those banners mixed in with other ads.
How does 10$/mo for a small banner work? Meaning, how often would it have to be displayed? Otherwise I think that approach doesn't lead far, namely, you can only make 10$ per month and advertising space.
$10 was an example price, but for most small sites you can't expect to make hundreds (or thousands) a month. I consider 'small' less than 1k uniques per day.
How you display the ads largely depends on your site and traffic. If you're only receiving a couple hundred pageviews each day, you'd want to have that ad showing as much as possible (to get a better price from the advertiser).
For a lot of these ads, you'd have multiple placements. ie. 4 ad spots for 125x125 pixel banners. On a site with a couple hundred pageviews it's realistic to assume you could get $15 for each of those ads (depending on the topic).
You're delusional if you think Adsense or other advertising networks will make you more than $15/mo. You're lucky if you get a $1 CPM (cost per 1k views) with most networks, assuming 6,000 views/month on a small site (~200/day * 30) - you can do the math there.
Again, this varies depending on the content. I worked for a small content network and we could charge $500/mo. for a banner spot that received about 20,000 views per month. But we only made $100-200 max with Adsense (across the whole site - roughly 45,000 impressions a month).
Just to chip in here, I know you were saying "I consider 'small' less than 1k uniques per day." to give an example, but this example is also most likely assuming you don't have targeted niche specific traffic. My 1K uniques/day pop culture tech/media site makes as much money as my 100 people/day very focused site on Apple products. Both are still serving Adsense only though that is only because I haven't gotten around to changing the latter site's advertising.
Also, $1 CPM with Adsense? If you are mainly a content based site (i.e. blogs) and place say two Adsense ads in prominent locations and maybe one Adsense link ad, you should easily top $5 CPM. I usually stay between $5 to $10 CPM for wordpress based sites.
The best way to make money on a small site is to go out and contact active advertisers (people advertising on sites like your own) and having a low (no-brainer) price for ads. $10-15/mo. for a small 125x125 px ad will bring you more than an adsense banner (for the majority of sites).
Affiliate marketing is also a great alternative. Find other products like your own and include those banners mixed in with other ads.